






                    TTHHEE IINNTTEERRCCAALL PPRROOGGRRAAMMMMIINNGG LLAANNGGUUAAGGEE
                         RREEVVIISSEEDD RREEFFEERREENNCCEE MMAANNUUAALL

                             _D_o_n_a_l_d _R_. _W_o_o_d_s
                                   _a_n_d
                              _J_a_m_e_s _M_. _L_y_o_n

                          _C_-_I_N_T_E_R_C_A_L _r_e_v_i_s_i_o_n_s_:
                               _L_o_u_i_s _H_o_w_e_l_l
                                   _a_n_d
                             _E_r_i_c _S_. _R_a_y_m_o_n_d



















































                                   - 2 -



       _1_.  _I_N_T_R_O_D_U_C_T_I_O_N

            "But  I  don't  want  to  go  among  mad people," Alice
            remarked.

            "Oh, you ca'n't help that," said the  Cat:  "We're  all
            mad here. I'm mad. You're mad."

            "How do you know I'm mad?" said Alice.
            "You must be," said the Cat, "or you wouldn't have come
            here."

       The  names  you  are  about to ignore are true. However, the
       story has been changed significantly. Any resemblance of the
       programming language portrayed  here  to  other  programming
       languages, living or dead, is purely coincidental.

       _1_._1  _O_r_i_g_i_n _a_n_d _P_u_r_p_o_s_e

       The  INTERCAL  programming language was designed the morning
       of May 26, 1972 by Donald R. Woods and  James  M.  Lyon,  at
       Princeton  University.  Exactly  when  in  the  morning will
       become apparent in the course of this manual.

       Eighteen years later (give or take a  few  months)  Eric  S.
       Raymond  perpetrated  a  UNIX-hosted  INTERCAL compiler as a
       weekend hack. The C-INTERCAL implementation has  since  been
       maintained  and  extended  by  an international community of
       technomasochists,  including  Louis  Howell,  Steve  Swales,
       Michael Ernst, and Brian Raiter.

       (There   was  evidently  an  Atari  implementation  sometime
       between  these  two;  notes  on  it  got  appended  to   the
       INTERCAL-72  manual.  The culprits have sensibly declined to
       identify themselves.)

       INTERCAL was inspired by one ambition: to  have  a  compiler
       language  which  has nothing at all in common with any other
       major language. By 'major' was meant anything with which the
       authors were at all familiar, e.g., FORTRAN,  BASIC,  COBOL,
       ALGOL,  SNOBOL, SPITBOL, FOCAL, SOLVE, TEACH, APL, LISP, and
       PL/I. For the most part, INTERCAL has remained true to  this
       goal,  sharing  only  the  basic elements such as variables,
       arrays, and  the  ability  to  do  I/O,  and  eschewing  all
       conventional  operations other than the assignment statement
       (FORTRAN "=").

       _1_._2  _A_c_r_o_n_y_m

       The full name of the compiler is "Compiler Language With  No
       Pronounceable  Acronym",  which  is,  for  obvious  reasons,
       abbreviated "INTERCAL".










                                   - 3 -



       _1_._3  _A_c_k_n_o_w_l_e_d_g_m_e_n_t_s

       The authors are deeply indebted to Eric M. Van and Daniel J.
       Warmenhoven, without whose unwitting assistance this  manual
       would still have been possible.

























































                                   - 4 -



       _2_.  _F_U_N_D_A_M_E_N_T_A_L _C_O_N_C_E_P_T_S

            "There's  nothing  like  eating hay when you're faint,"
            the White King remarked to Alice, as he munched away.

            "I should think throwing cold water over you  would  be
            better," Alice suggested: "-- or some sal-volatile."

            "I  didn't  say  there  was  nothing  _b_e_t_t_e_r," the King
            replied. "I said there  was  nothing  _l_i_k_e  it."  Which
            Alice did not venture to deny.

       In  this  section an attempt is made to describe how and why
       INTERCAL may be used; i.e., what it is like and what  it  is
       good for.

       _2_._1  _S_a_m_p_l_e _P_r_o_g_r_a_m

       Shown  below  is  a relatively simple INTERCAL program which
       will read in 32-bit unsigned integers, treat them as signed,
       2's-complement numbers, and print out their absolute values.
       The program exits if the absolute value  is  zero.  Note  in
       particular  the inversion routine (statements 6 through 14),
       which could be greatly simplified if the subroutine  library
       (see section ) were used.

       A more detailed analysis of a program is made in section
        of this manual.


































                                   - 5 -



               DO (5) NEXT
           (5) DO FORGET #1
               PLEASE WRITE IN :1
               DO .1 <- 'V-":1~'#32768c/#0'"c/#1'~#3
               DO (1) NEXT
               DO :1 <- "'V-":1~'#65535c/#0'"c/#65535'
                       ~'#0c/#65535'"c/"'V-":1~'#0c/#65535'"
                       c/#65535'~'#0c/#65535'"
               DO :2 <- #1
               PLEASE DO (4) NEXT
           (4) DO FORGET #1
               DO .1 <- "V-':1~:2'c/#1"~#3
               DO :1 <- "'V-":1~'#65535c/#0'"c/":2~'#65535
                       c/#0'"'~'#0c/#65535'"c/"'V-":1~'#0
                       c/#65535'"c/":2~'#0c/#65535'"'~'#0c/#65535'"
               DO (1) NEXT
               DO :2 <- ":2~'#0c/#65535'"
                       c/"'":2~'#65535c/#0'"c/#0'~'#32767c/#1'"
               DO (4) NEXT
           (2) DO RESUME .1
           (1) PLEASE DO (2) NEXT
               PLEASE FORGET #1
               DO READ OUT :1
               PLEASE DO .1 <- 'V-"':1~:1'~#1"c/#1'~#3
               DO (3) NEXT
               PLEASE DO (5) NEXT
           (3) DO (2) NEXT
               PLEASE GIVE UP

       _2_._2  _U_s_e_s _f_o_r _I_N_T_E_R_C_A_L

       INTERCAL's  main  advantage over other programming languages
       is its strict simplicity. It has few capabilities, and  thus
       there  are  few restrictions to be kept in mind. Since it is
       an exceedingly easy language to learn, one might  expect  it
       would  be a good language for initiating novice programmers.
       Perhaps surprising, then, is the fact that it would be  more
       likely  to  initiate a novice into a search for another line
       of work. As it turns out, INTERCAL  is  more  useful  (which
       isn't   saying   much)   as   a  challenge  to  professional
       programmers.  Those who doubt this need only refer  back  to
       the  sample  program  in section . This 23-statement program
       took somewhere from 15 to 30 minutes to write,  whereas  the
       same objectives can be achieved by single-statement programs
       in either SNOBOL;

               PLEASE INPUT POS(0) ('-' ! '')
               + (SPAN('0123456789') $ OUTPUT)
               + *NE(OUTPUT) :S(PLEASE)F(END)

       or APL;

               [1] ->0!=[]<-|[]









                                   - 6 -



       Admittedly,  neither  of  these  is  likely  to  appear more
       intelligible  to  anyone  unfamiliar  with   the   languages
       involved,  but  they took roughly 60 seconds and 15 seconds,
       respectively, to write. Such is the  overwhelming  power  of
       INTERCAL!

       The other major importance of INTERCAL lies in its seemingly
       inexhaustible capacity for amazing one's fellow programmers,
       confounding  programming shop managers, winning friends, and
       influencing people. It is a well-known and  oft-demonstrated
       fact that a person whose work is incomprehensible is held in
       high  esteem.  For  example,  if  one were to state that the
       simplest way to store a value of 65536 in a 32-bit  INTERCAL
       variable is:

               DO :1 <- #0c/#256

       any  sensible  programmer  would  say  that that was absurd.
       Since this is indeed the  simplest  method,  the  programmer
       would  be  made  to  look  foolish in front of his boss, who
       would of course happened to turn up, as bosses are  wont  to
       do.  The  effect  would  be  no  less  devastating  for  the
       programmer having been correct.







































                                   - 7 -



       _3_.  _D_E_S_C_R_I_P_T_I_O_N

            "I quite agree with you," said the  Duchess;  "and  the
            moral  of  that is -- 'Be what you would seem to be' --
            or, if you'd like it put more simply -- 'Never  imagine
            yourself  not to be otherwise than what it might appear
            to others that what you were or might have been was not
            otherwise than what you had been would have appeared to
            them to be otherwise."
            "I think I should understand that better,"  Alice  said
            very  politely, "if I had it written down: but I ca'n't
            quite follow it as you say it."

            "That's nothing to what I could say if  I  chose,"  the
            Duchess replied, in a pleased tone.

       The  examples of INTERCAL programming which have appeared in
       the preceding sections of this manual have  probably  seemed
       highly  esoteric to the reader unfamiliar with the language.
       With the aim of making them  more  so,  we  present  here  a
       description of INTERCAL.

       _3_._1  _V_a_r_i_a_b_l_e_s

       INTERCAL  allows  only  2  different types of variables, the
       1166--bbiitt  iinntteeggeerr  and  the   3322--bbiitt   iinntteeggeerr..    These   are
       represented  by  a  spot  (.) or two-spot (:), respectively,
       followed by any  number  between  1  and  65535,  inclusive.
       These  variables may contain only non-negative numbers; thus
       they have the respective ranges of values: 0 to 65535 and  0
       to   4294967295.  Note:  .123  and  :123  are  two  distinct
       variables. On the other hand, .1 and  .0001  are  identical.
       Furthermore, the latter may _n_o_t be written as 1E-3.

       _3_._2  _C_o_n_s_t_a_n_t_s

       CCoonnssttaannttss  are  16-bit  values  only and may range from 0 to
       65535. They are prefixed by a mesh (#).  Caution!  Under  no
       circumstances confuse the mesh with the interleave operator,
       except under confusing circumstances!

       _3_._3  _A_r_r_a_y_s

       AArrrraayyss are represented by a tail (,) for 16-bit values, or a
       hybrid (;) for 32-bit values, followed by a number between 1
       and  65535,  inclusive.  The  number is suffixed by the word
       SUB, followed by the  subscripts,  separated  optionally  by
       spaces.  Subscripts  may be any expressions, including those
       involving subscripted variables. This occasionally leads  to
       ambiguous  constructions, which are resolved as discussed in
       section .  Definition of array dimensions will be  discussed
       later  in greater detail, since discussing it in less detail
       would be difficult. As before, ,123 and ;123  are  distinct.
       In  summary,  .123,  :123,  #123,  ,123,  and  ;123  are all








                                   - 8 -



       distinct.

       _3_._4  _O_p_e_r_a_t_o_r_s

       INTERCAL recognizes 5 operators -- 2 binary and 3 unary [1].
       Please be kind to  our  operators:  they  may  not  be  very
       intelligent,  but  they're all we've got.  In a sense, all 5
       operators are binary, as they are all bit-oriented,  but  it
       is not our purpose here to quibble about bits of trivia.

       _3_._4_._1  _B_i_n_a_r_y _O_p_e_r_a_t_o_r_s

       The binary operators are iinntteerrlleeaavvee (also called mmiinnggllee) and
       sseelleecctt,  which are represented by a change (c/) and a sqiggle
       [sic]   (~),   respectively.    (In    C-INTERCAL's    ASCII
       environment,  EBCDIC c/ is replaced by a big money ($), but c/
       can be used if encoded in  Latin-1  as  \0xA2  or  UTF-8  as
       0xC2A2.)

       The interleave operator takes two 16-bit values and produces
       a  32-bit  result  by  alternating the bits of the operands.
       Thus, #65535c/#0 has the 32-bit binary form  101010....10  or
       2863311530  decimal,  while  #0c/#65535 = 0101....01 binary =
       1431655765 decimal, and #255c/#255 is equivalent to #65535.

       The select operator takes from the first  operand  whichever
       bits  correspond  to  1's  in  the second operand, and packs
       these bits to the right in the result.   Both  operands  are
       automatically  padded  on  the  left  with  zeros to 32 bits
       before the selection takes place, so the variable types  are
       unrestricted.  If more than 16 bits are selected, the result
       is  a  32-bit  value,  otherwise  it  is a 16-bit value. For
       example, #179~#201 (binary value 10110011~11001001)  selects
       from the first argument the 8th, 7th, 4th, and 1st from last
       bits,  namely,  1001,  which = 9. But #201~#179 selects from
       binary 11001001 the 8th, 6th, 5th, 2nd, and  1st  from  last
       bits,  giving  10001 = 17. #179~#179 has the value 31, while
       #201~#201 has the value 15.

       Perhaps a simpler way of understanding the operation of  the
       select  operator  would  be  to examine the logic diagram in
       Figure 1, which performs the select operation upon two 8-bit
       values, A and B.  The  gates  used  are  Warmenhovian  logic
       gates,  which  means  the outputs have four possible values:
       low, high, undefined (value of an uninitialized  flip-flop),
       and oscillating (output of a NOR gate with one input low and
       the  other  input connected to the output). These values are
       represented symbolically by '0', '1', '?', and 'O|'.  Note in
       particular that, while NOT-0 is 1 and NOT-1 is 0 as in  two-
       valued  logic,  NOT-?  is ? and NOT-O| is O|. The functions of

       ____________________

       1. Other operators are also available with C-INTERCAL's non-
          standard dialects; see section .







                                   - 9 -



       the various gates are listed in Table 1.

       [Warning: The following picture will be garbled or  missing.
       Get a better output device.]


























































                                  - 10 -



        --+-+----     --+----  +--+----   --+----  +--+----   +-+
      A1   | | 1  +-+--+-+ 2  +-++-+ 3  ++-+-+ 3  ++|--+ 1  +--| |
      B --+++    | |--+-+    | || |    ||||++    |||| |    |  | |  TO
      1   +++------++-+-+------+|-+---  +++++-----++|-+---    | +--NEW
           +-------++-+---------+-------+++++-----+ |         | | YORK
          +-+------++-+-+-----+ | +---- ||| +-----+ | +----   | |  TO
      A2 --+-+    | || +-+    || --+    |+++-+    |+-+-+    |  | +--NEW
        --+-+ 1  +-++-+-+ 2  +++--+ 7  +-++-+ 3  +--+-+ 2  +--| | YOTROK
      B2   |-+---   |||+-+---  || -+---   |+-+------++-+-------| +--NEW
          +--------+++-+------++---------+--------+|+---------| | YORK
          +-+------+++-++-----++--+-----+| ++-----++--+-----+ | |  TO
      A --+-+    | +++-++    |++--+    |++-++    ||+--+    || |B +--NEW
      3     | 1  +-+++-+| 2  +-++-+ 3  +-++++ 3  ++++-+ 3  ++-| | YORK
      B3 --+-+---  ||||+++---  |||-+---  ++|++---  ||+++---  | | |  TO
          +-------++++++------+++-------++++------++++------+-|U +--NEW
          +-+-----+++-+++-----+++-+-----+++||     ++++|     | | | YORK
      A --+-+----|||| ||+----||++-+----||++++----|+++++----|| |S |  TO
      4     | 1  +++++|++ 2  ++++-+ 7  ++++++ 3  ++++-+ 4  ++-| +--NEW
      B --+-+---  ||||+-+---  ||+-+---  |||++--- ++--++---  | | | YOTROK
      4   |       |||+++      ++--+ +---++++++++++|+-+------+ | +--NEW
          +-------+++-++-------++++-+--+||+++++++-++++--+     | | YORK
        --+-+-----+++-+++-----+++++-+--+++-++++++ +++++-+--   |L |  TO
      A5     | 1  ++++++++ 2  ++++++ 3  +++ ++ 3  +-++++ 5  +--| +--NEW
      B --+-+    |||+++++    |  |||    ||| ||    |++++|    |  | | YORK
      5   |-+---  |||||++-------|++----+|+--+-----+++++-------|I |  TO
          +-------+++++--------++------++++ +---  |+++        | +--NEW
          +-+-----+++++-+-----+|| +----++++++-----+|||+----   |N | YORK
      A6 --+-+    |||-++++    |+++-+    |+++++    | ++++    |  | |  TO
        --+-+ 1  +++-++++ 2  ++++-+ 3  +-++++ 4  ++++++ 4  +--| +--NEW
      B6   |-+---  +++++++---  +++-+-----+||++-----+++++-------|E | YORK
          +--------++++--------++------+|||       ++-+        | +--TO
          +-+------++++-+-----+|| +----++++++---- ||  +----   | | NEW
      A --+-+    | -+++-+    |+++-+    |+++++    ||+--+    |  | | YOTROK
      7     | 1  +--+|+-+ 2  +-++-+ 3  ++|+++ 4  ++-+-+ 5  +--| +--NEW
      B7 --+-+---   ||++-+---   ||++---  || ++---  --+++---    | | YORK
          +----+---++++--------+++------++ +------+-++------+-| |  TO
          +-+--+---++++-+-------+||     |  ||     |  ||     | | +--NEW
      A --+-+----| |+++-+----|+-+++----|+--++----||+--+----|| | | YORK
      8     | 1  +-+ |+-+ 2  ++ +++ 4  ++ +++ 3  ++++-+ 5  ++-|8 |  TO
      B --+-+---     +--+---  |  ++---  | |++---  | |-+---  | | +--NEW
      8   +----------------+  ++-+      +-++---+ ++-+------+| | | YORK
                           +--+++--------+||   +-++++------++-| |  TO
            +----  +-+--+-----+++-+----  ++++----+|++-+----++-| +--NEW
            | 6  +-+ +--+ 2  ++-+-+ 7  +-++-+ 3  +++|++ 4  ++-| | YOTROK
            |    |  -+--+    |+---+    |  | |    || |||    || | +-P-HILA-
           -+---    |  -+---     -+---    |-+---  +-+++---  | | |DELPHIA
                    +---------------------+---------+-------+-| |
            +----   |+--+---------+------++-+-----+   +----   | |
            |    |  ++--+    |  +-+    | |--+    ||+--+    |  | |
            | 6  +--++--+ 1  +-++-+ 1  +-+--+ 1  +++--+ 1  ++ | |
           -+---       -+--- --++-+---   | -+---  |  -+-----+-+-+
                               ---                         ---
                       FIGURE 1. CIRCUITOUS DIAGRAM


       






                                  - 11 -



          __________________________________________________________
         |\                                                         \
         | \ 1. Logic gate.  Inputs A, B.  Output O = AB.            \
         |  \                                                         \
         | \ \ 2. Logic gate.  Inputs A, B, C.  Output O = A+BC.       \
         | |\ \                                                         \
         | | \ \ 3. Logic gate.  Inputs A, B.  Output O = A+AB.          \
         | |  \ \                                                         \
         | |  |\ \ 4. Logic gate.  Inputs A, B.  Output O = AB O+ -(A+-B)   \
         | |  | \ \                                                         \
         | |  |  \ \ 5. Logic gate.  Inputs A, B.  Output O = AO+A + AA       \
         | |  |   \ \                                                         \
         | |  |    \ \ 6. Uninitialized flip-flop.  Inputs none.  Output O = ? \
         | |  |     \ \                                                         \
         | |  |      \ \ 7. Flip-flop-flap.  Inputs A, B, C.  Output O = 1 if    \
         | |  |       \ \    A=0 or B+C=0 and A=1.  O = 0 if AC=1, B=0.  O = O| if \
         | |  |        \ \    AB=1, C=0.  O = ? if ABC=1.  O as yet undetermined   \
         | |  |         \ \    for other Warmenhovian inputs.  See Figure 2.        \
         | |  |          \ \                                                         \
         | |  |           \ \ 8. Bus line.                                            \
         | |  |            \ \_________________________________________________________\
         | |  |             \ |                                                         |
         | |  |             | |  _____________________________________________________  |
         | |  |             | |  |                              | |  |             | |  |
         | |  |             | |  |                              | |  |             | |  |
         | |  |             | |  |                              | |  |             | |  |
         | |  |             | |  |                              | |  |             | |  |
         | |  |             | |  |                              | |  |             | |  |
          \|__|             | |  |                               \|__|             | |  |
                            | |  |                                                 | |  |
                            | |  |                                                 | |  |
                            | |  |                                                 | |  |
                            | |  |                                                 | |  |
                            | |  |                                                 | |  |
                            | |  |                                                 | |  |
                            | |  |                                                 | |  |
                            | |  |                                                 | |  |
                            | |  |                                                 | |  |
                            | |  |                                                 | |  |
                            | |  |                                                 | |  |
                            | |  |                                                 | |  |
                            | |  |                                                 | |  |
                            | |  |                                                 | |  |
                            | |  |                                                 | |  |
                            | |  |                                                 | |  |
                            | |  |                                                 | |  |
                            | |  |                                                 | |  |
                             \|__|                                                  \|__|

                 Table 1.  Logical (and other) functions.





       






                                  - 12 -



       [Warning:  The following picture will be garbled or missing.
       Get a better output device.]










       -------------------------+----
      A                     +---+    |----+------------D
                            |   |    |    |
                                +----



                            |   |            |
                            +---+----        |
      B-------------------------+    |----+  |
                                +----|    |  |
                                          |  |
                                          |  |
                                          |  |
                                          |  |
                                |         |  |
      C-------------------------+----|    |  |
               +----------------+    |--+ |  |
               |                +----   | |  |
               |                        | |  |
               |                             |
               |                             |
               |                             |
               |            | | |            |
               |            | +-+----|       |
               |            +---+ +- +-------+
               |                +-+--
         1-----+










                         FIGURE 2. FLIP FLAP FLOP




       






                                  - 13 -



       [Warning: The following picture will be garbled or  missing.
       Get a better output device.]
           +---+
       ----+   |
       ----+   +----
       ----+   |
       ----+   +----
           |   |
       ----+   +----
       ----+   |
       ----+   +----
       ----+   |                     GATE TYPE 9.  BLACK BOX
       ----+ 9 +----                 INPUTS A1-8,  B1-8.
       ----+   |                     OUTPUT O1-8 = A1-8~B1-8
       ----+   +----
       ----+   |
       ----+   +----
           |   |
       ----+   +----
       ----+   |
       ----+   +----
       ----+   |
           +---+










                     FIGURE 1  (CONTINUED).  NEW YORK





















       






                                  - 14 -



       _3_._4_._1_._1  _R_e_t_u_r_n _t_y_p_e _o_f _S_E_L_E_C_T

       INTERCAL-72 defined the return type of a select operation to
       depend  on  the  number  of  bits  selected.  The C-INTERCAL
       compiler takes the easier route of defining the return  type
       to  be  that of the right operand, independent of its actual
       value. This form has the advantage that  all  types  can  be
       determined  at  compile  time.   Putting  in  run-time type-
       checking would add significant overhead and complication, to
       effect a very minor change in language semantics.

       The only time this distinction makes any difference is  when
       a  unary  operator  is  applied  to  the select result. This
       happens  extremely  rarely  in  practice,  the  only   known
       instance  being the 32-bit greater-than test in the standard
       library, where an XOR operator is applied to the  result  of
       selecting  a  number against itself. The INTERCAL-72 authors
       first select the result against #65535c/#65535 to insure that
       XOR sees a 32-bit value.  With  the  current  compiler  this
       extra step is unnecessary, but harmless.

       The  cautious  programmer  should  write  code that does not
       depend on the compiler  version  being  used.  We  therefore
       suggest  the  following guideline for determining the select
       return type:

       A select operation with a 16-bit  right  operand  returns  a
       16-bit  value.  The return type of a select operation with a
       32-bit right operand is undefined, but is guaranteed  to  be
       an  acceptable  input to a mingle operation so long as 16 or
       fewer bits are actually selected. Correct  code  should  not
       depend on whether the return type is 16 or 32 bits.

       _3_._4_._2  _U_n_a_r_y _O_p_e_r_a_t_o_r_s

       The unary operators are & (logical AANNDD), V (logical OORR), and
       V-   (logical  XXOORR).  This  last  character  is  obtained  by
       overpunching a worm (-) on a V (V).  (In  C-INTERCAL,  V-  is
       replaced  by what (?). The compiler recognizes V<backspace>-
       as a valid equivalent,  in  case  you  are  concerned  about
       compatibility  with the Princeton compiler.  In version 0.20
       and later, the Unicode character U+2200 FOR ALL, which looks
       exactly like V<backspace>- or an  upside-down  `A'  is  also
       accepted  in  UTF-8 form.)  The operator is inserted between
       the spot, two-spot, mesh, or what-have-you, and the integer,
       thus: .&123, #V-123. Multiple  unary  operators  may  not  be
       concatenated,  thus the form #V-&123 is invalid. This will be
       covered later when precedence is discussed. These  operators
       perform  their respective logical operations on all pairs of
       adjacent bits, the result from the first and last bits going
       into the first bit of the result.  The  effect  is  that  of
       rotating  the  operand  one  place  to the right and ANDing,
       ORing, or XORing with its initial value. Thus, #&77  (binary
       =  1001101)  is  binary 0000000000000100 = 4, #V77 is binary

       






                                  - 15 -



       1000000001101111   =   32879,    and    #V-77    is    binary
       1000000001101011 = 32875.

       _3_._4_._3  _P_r_e_c_e_d_e_n_c_e

       Precedence of operators is as follows:










       (The remainder of this page intentionally left blank)[2]


































       ____________________

       2. Keep  in  mind  that the aim in designing INTERCAL was to
          have no precedents.







                                  - 16 -



       This precedence  (or  lack  thereof)  may  be  overruled  by
       grouping  expressions between pairs of sparks (') or rabbit-
       ears    (").    Thus    '#165c/#203'~#358    (binary    value
       '10100101c/11001011'~101100110)   has   the   value  15,  but
       #165c/'#203~#358' has the value 34915, and #165c/#203~#358  is
       invalid  syntax  and is completely valueless (except perhaps
       as an educational tool to the programmer). A unary  operator
       is  applied  to  a  sparked  or  rabbit-eared  expression by
       inserting the operator  immediately  following  the  opening
       spark  or  ears.  Thus, the invalid expression #V-&123, which
       was  described  earlier,  could  be  coded  as  'V-#&123'  or
       'V-"&#123"'.   Note:  In  the  interests  of  simplifying the
       sometimes  overly-complex  form  of  expressions,   INTERCAL
       allows  a  spark-spot combination ('.) to be replaced with a
       wow (!). Thus '.1~.2' is equivalent to !1~.2', and  'V.1c/.2'
       is equivalent to "V!1c/.2'".

       Combining  a rabbit-ears with a spot to form a rabbit (".) is
       not permitted, although the programmer is  free  to  use  it
       should   he  find  an  EBCDIC  reader  which  will  properly
       translate a 12-3-7-8 punch.

       Sparks and/or rabbit-ears must also be used  to  distinguish
       among  such  otherwise  ambiguous  subscripted and multiply-
       subscripted expressions as:

               ,1 SUB #1 ~ #2
               ,1 SUB ,2 SUB #1 #2 #3
               ,1 SUB " ,2 SUB " ,3 SUB #1 " #2 " " #3 "

       The third case may be isolated into either of  its  possible
       interpretations by simply changing some pairs of rabbit-ears
       to  sparks,  instead  of  adding more ears (which would only
       confuse the issue further). Ambiguous cases are  defined  as
       those  for  which the compiler being used finds a legitimate
       interpretation which is different from that which  the  user
       had in mind. See also section .


















       






                                  - 17 -



       _4_.  _S_T_A_T_E_M_E_N_T_S

            "There's glory for you!"

            "I don't know what you mean by 'glory,'" Alice said.

            Humpty  Dumpty  smiled  contemptuously.  "Of course you
            don't -- till I tell  you.  I  meant  'there's  a  nice
            knock-down argument for you!'"
            "But   'glory'   doesn't   mean   'a   nice  knock-down
            argument.'" Alice objected.

            "When _I use a word," Humpty Dumpty said,  in  a  rather
            scornful  tone, "it means just what I choose it to mean
            -- neither more nor less."

       In  this  section  is  described  the  format  of   INTERCAL
       statements.

       _4_._1  _G_e_n_e_r_a_l _F_o_r_m_a_t

       Statements  may  be  entered in 'free format'. That is, more
       than one statement  may  occur  on  a  single  card,  and  a
       statement may begin on one card and end on a later one. Note
       that  if  this  is  done, all intervening cards and portions
       thereof must be  part  of  the  same  statement.  That  this
       restriction  is  necessary  is immediately apparent from the
       following example of what might occur if statements could be
       interlaced.

               DO .1 <- ".1c/'&:51~"#V-1c!12~;&75SUB"V-'V.1~
               DO .2 <- '"!1c/"&';V-79SUB",&7SUB:173"'~!V-9c/
               .2'c/,&1SUB:5~#33578"'"'"~'#65535c/"V-'V#&85'"'
               #8196'"'~.1"c/.2'~'#&5c/"'#1279c/#4351'~#65535"'

       The above statements are obviously  meaningless.  (For  that
       matter, so are the statements

               DO .1 <- ".1c/"&:51~"#V-1c/!12~;&75SUB"V-'V.1~
               .2'c/,&1SUB:5~#333578"'"'"~#65535c/"V-'V#&85'"'
               DO .2 <- '"!1c/"&';V-79SUB",&7SUB:173"'~!V-9c/
               #8196'"'~.1"c/.2'~'#&5c/"'#1279c/#4351'~#65535"'

       but this is not of interest here.)

       Spaces  may be used freely to enhance program legibility (or
       at least reduce program illegibility), with the  restriction
       that  no  word  of a statement identifier (see section ) may
       contain any spaces.

       _4_._2  _L_a_b_e_l_s

       A statement may begin with a llooggiiccaall lliinnee llaabbeell enclosed  in
       wax-wane  pairs (()). A statement may not have more than one

       






                                  - 18 -



       label, although it is possible to omit the label entirely. A
       line label is any integer from 1 to  65535,  which  must  be
       unique  within each program. The user is cautioned, however,
       that many line labels between 1000 and 1999 are used in  the
       INTERCAL System Library functions.

       _4_._3  _I_d_e_n_t_i_f_i_e_r_s _a_n_d _Q_u_a_l_i_f_i_e_r_s

       After  the  line  label  (if  any),  must  follow one of the
       following statement identifiers: DO, PLEASE, or  PLEASE  DO.
       These  may be used interchangeably to improve the aesthetics
       of the program. The identifier is then followed  by  either,
       neither,  or  both  of  the  following  optional  parameters
       (qualifiers): (1) either of the  character  strings  NOT  or
       N'T,   which   causes  the  statement  to  be  automatically
       abstained from (see section ) when execution begins, and (2)
       a number between 0 and 100, preceded  by  a  double-oh-seven
       (%),  which  causes the statement to have only the specified
       percent chance of being executed each time it is encountered
       in the course of execution.

       _4_._4  _S_t_a_t_e_m_e_n_t_s

       Following  the  qualifiers  (or,  if  none  are  used,   the
       identifier)  must  occur  one  of  the  14 valid operations.
       (Exception: see section .) These are described  individually
       in sections
        through .

       _4_._4_._1  _C_a_l_c_u_l_a_t_e

       The  INTERCAL  equivalent  of  the half-mesh (=) in FORTRAN,
       BASIC, PL/I, and others, is  represented  by  an  angle  (<)
       followed  by  a  worm  (-). This combination is read 'gets'.
       32-bit variables may be assigned 16-bit  values,  which  are
       padded  on  the left with 16 zero bits. 16-bit variables may
       be assigned 32-bit values only if the  value  is  less  than
       65535.  Thus,  to  invert  the  least significant bit of the
       first element of 16-bit 2-dimensional array  number  1,  one
       could write:

       ,1SUB#1#1 <- 'V-",1SUB#1#1"c/#1'~'#0c/#65535'

       Similarly  to  SNOBOL  and SPITBOL, INTERCAL uses the angle-
       worm to define the dimensions of  arrays.  An  example  will
       probably  best  describe the format.  To define 32-bit array
       number 7 as 3-dimensional, the first dimension being  seven,
       the second being the current value of 16-bit variable number
       seven,  and the third being the current value of the seventh
       element  of  16-bit  array  number  seven  (which  is   one-
       dimensional)  mingled  with  the  last  three bits of 32-bit
       variable number seven, one would  write  (just  before  they
       came to take him away):


       






                                  - 19 -



       ;7 <- #7 BY .7 BY ",7SUB#7"c/':7~#7'

       This is, of course, different from the statement:

       ;7 <- #7 BY .7 BY ,7SUB"#7c/':7~#7'"

       INTERCAL  also permits the redefining of array dimensioning,
       which is done the same way as is the  initial  dimensioning.
       All   values   of   items   in   an   array  are  lost  upon
       redimensioning, unless they have been STASHed  (see  section
       ),  in  which  case  restoring  them  also  restores the old
       dimensions.

       _4_._4_._2  _N_E_X_T

       The NEXT statement is used both for subroutine calls and for
       unconditional transfers. This statement takes the form:

       DO (label) NEXT

       (or, of course,

       PLEASE DO (label) NEXT

       etc.), where (label) represents any logical line label which
       appears in the program. The effect of such a statement is to
       transfer control to the statement specified, and to store in
       a push down list (which is  initially  empty)  the  location
       from  which  the  transfer takes place. Items may be removed
       from this list and may be discarded or used to return to the
       statement immediately following the  NEXT  statement.  These
       operations are described in sections
        and
        respectively.   The  programmer  is  generally  advised  to
       discard any stack  entries  which  he  does  not  intend  to
       utilize,  since the stack has a maximum depth of 79 entries.
       A program's attempting to initiate an 80th level of  NEXTing
       will  result  in  the  fatal  error  message,  "PROGRAM  HAS
       DISAPPEARED INTO THE BLACK LAGOON."

       _4_._4_._3  _F_O_R_G_E_T

       The statement PLEASE FORGET exp, where  exp  represents  any
       expression   (except  colloquial  and  facial  expressions),
       causes the expression to be  evaluated,  and  the  specified
       number  of  entries to be removed from the NEXTing stack and
       discarded. An attempt to FORGET more levels of NEXTing  than
       are  currently  stacked  will cause the stack to be emptied,
       and no error condition is indicated.  This  is  because  the
       condition  is not considered to be an error. As described in
       section , it is good programming practice to  execute  a  DO
       FORGET  #1  after using a NEXT statement as an unconditional
       transfer, so that the stack does not get cluttered  up  with
       unused entries:

       






                                  - 20 -



               DO (123) NEXT
               .
               .
         (123) DO FORGET #1

       _4_._4_._4  _R_E_S_U_M_E

       The  statement  PLEASE  RESUME  exp  has  the same effect as
       FORGET, except that  program  control  is  returned  to  the
       statement  immediately  following  the  NEXT statement which
       stored in the stack the last entry to be removed. Note  that
       a  rough  equivalent of the FORTRAN computed GO TO and BASIC
       ON exp GO TO is performed by a sequence of the form:

               DO (1) NEXT
               .
               .
           (1) DO (2) NEXT
               PLEASE FORGET #1
               .
               .
           (2) DO RESUME .1

       Unlike the FORGET  statement,  an  attempt  to  RESUME  more
       levels  of  NEXTing than has been stacked will cause program
       termination. See also section .

       _4_._4_._5  _S_T_A_S_H

       Since  subroutines  are  not   explicitly   implemented   in
       INTERCAL,  the  NEXT  and  RESUME statements must be used to
       execute common routines. However, as  these  routines  might
       use  the same variables as the main program, it is necessary
       for them to save the values of any  variables  whose  values
       they   alter,  and  later  restore  them.  This  process  is
       simplified by the STASH statement, which  has  the  form  DO
       STASH  list,  where  list represents a string of one or more
       variable or array names,  separated  by  intersections  (+).
       Thus

       PLEASE STASH .123+:123+,123

       stashes  the  values  of two variables and one entire array.
       The values are left intact, and copies thereof are saved for
       later retrieval by (what else?)  the RETRIEVE statement (see
       section ). It is not possible to STASH single array items.

       _4_._4_._6  _R_E_T_R_I_E_V_E

       PLEASE RETRIEVE list restores the previously STASHed  values
       of  the  variables  and arrays named in the list. If a value
       has been stashed more than once, the most  recently  STASHed
       values are RETRIEVEd, and a second RETRIEVE will restore the
       second  most recent values STASHed. Attempting to RETRIEVE a

       






                                  - 21 -



       value which has not been STASHed will result  in  the  error
       message, "THROW STICK BEFORE RETRIEVING."

       _4_._4_._7  _I_G_N_O_R_E

       The   statement   DO   IGNORE  list  causes  all  subsequent
       statements to have no effect upon  variables  and/or  arrays
       named in the list. Thus, for example, after the sequence

               DO .1 <- #1
               PLEASE IGNORE .1
               DO .1 <- #0

       16-bit  variable  number  1  would  have the value 1, not 0.
       Inputting (see section ) into an IGNOREd variable  also  has
       no  effect.  The  condition  is  annulled  via  the REMEMBER
       statement (see section ). Note  that,  when  a  variable  is
       being   IGNOREd,  its  value,  though  immutable,  is  still
       available for use in expressions and the like.

       Though the INTERCAL-72 manual laid down that the value of an
       IGNOREd variable cannot change, it was unclear about whether
       or not a  statement  which  appears  to  change  an  IGNOREd
       variable  is  executed or not. This may appear to be a "If a
       tree falls in the forest ..." type of question, but  if  the
       statement in question has other side effects it is not.

       Since another mechanism already exists for ABSTAINing from a
       statement, C-INTERCAL's IGNORE only prevents the changing of
       the  specific variable in question, not the execution of the
       entire statement. In the present  version  of  the  language
       this  only  makes  a  difference for the WRITE IN (see ) and
       RETRIEVE (see ) statements. Attempting to  WRITE  IN  to  an
       IGNOREd  variable  will  cause  a number to be read from the
       input, which will be discarded since it cannot be stored  in
       the  variable.   Using  RETRIEVE on an IGNOREd variable will
       pop the variable's stash stack without actually changing its
       value.

       _4_._4_._8  _R_E_M_E_M_B_E_R

       PLEASE REMEMBER list terminates the  effect  of  the  IGNORE
       statement for all variables and/or arrays named in the list.
       It  does not matter if a variable has been IGNOREd more than
       once, nor is it an  error  if  the  variable  has  not  been
       IGNOREd at all.

       _4_._4_._9  _A_B_S_T_A_I_N

       INTERCAL contains no simple equivalent to an IF statement or
       computed  GO  TO,  making  it  difficult  to combine similar
       sections of code into a single  routine  which  occasionally
       skips  around  certain statements. The IGNORE statement (see
       section ) is helpful in some cases, but a more viable method

       






                                  - 22 -



       is often required. In keeping  with  the  goal  of  INTERCAL
       having  nothing  in  common with any other language, this is
       made possible via the ABSTAIN statement.

       This statement takes on one of two forms. It may not take on
       both at any one time. DO ABSTAIN  FROM  (label)  causes  the
       statement   whose  logical  line  label  is  (label)  to  be
       abstained from. PLEASE ABSTAIN FROM gerund list  causes  all
       statements of the specified type(s) to be abstained from, as
       in

             PLEASE ABSTAIN FROM STASHING
             PLEASE ABSTAIN FROM IGNORING + FORGETTING
             PLEASE ABSTAIN FROM NEXTING
          or PLEASE ABSTAIN FROM CALCULATING

       Statements  may  also be automatically abstained from at the
       start of execution via the NOT or N'T parameter (see section
       ).

       If, in the course of execution, a statement  is  encountered
       which  is  being  abstained  from, it is ignored and control
       passes to the next statement in the program (unless it, too,
       is being abstained from).

       The statement DO ABSTAIN FROM ABSTAINING is perfectly valid,
       as is DO ABSTAIN FROM REINSTATING (although this  latter  is
       not  usually recommended). However, the statement DO ABSTAIN
       FROM GIVING UP is not accepted, even though  DON'T  GIVE  UP
       is.

       _4_._4_._1_0  _R_E_I_N_S_T_A_T_E

       The  REINSTATE  statement,  like  the  ABSTAIN,  takes as an
       argument either a line label or a gerund list. No other form
       of argument is permitted. For example, the following  is  an
       invalid argument:

               Given: x!=0, y!=0,  Prove: x+y=0
               Since x!=0, then x+1!=1, x+a!=a, x+y!=y.
               But what is y? y is anything but 0.
               Thus x+y != anything but 0.
               Since x+y cannot equal anything but 0, x+y=0.
                                                                Q.E.D.

       REINSTATEment nullifies the effects of an abstention. Either
       form  of  REINSTATEment  can  be used to "free" a statement,
       regardless of whether the statement was  abstained  from  by
       gerund  list,  line  label,  or  NOT. Thus, PLEASE REINSTATE
       REINSTATING is  not  necessarily  an  irrelevant  statement,
       since it might free a DON'T REINSTATE command or a REINSTATE
       the  line  label  of  which  was abstained from. However, DO
       REINSTATE GIVING UP is invalid, and attempting to  REINSTATE
       a  GIVE UP statement by line label will have no effect. Note

       






                                  - 23 -



       that this insures that DON'T GIVE UP will always be  a  "do-
       nothing" statement.

       _4_._4_._1_1  _G_I_V_E _U_P

       PLEASE  GIVE  UP  is used to exit from a program. It has the
       effect of a PLEASE RESUME #80. DON'T GIVE UP,  as  noted  in
       section , is effectively a null statement.

       _4_._4_._1_2  _I_n_p_u_t

       Input  is  accomplished with the statement DO WRITE IN list,
       where list represents a string of variables and/or  elements
       of   arrays,   separated   by   intersections.  Numbers  are
       represented on cards, each number on  a  separate  card,  by
       spelling  out  each  digit  (in  English) and separating the
       digits with one or more spaces. A zero (0) may be spelled as
       either ZERO or OH.  Thus the range of (32-bit) input  values
       permissible  extends from ZERO (or OH) through FOUR TWO NINE
       FOUR NINE SIX SEVEN TWO NINE FIVE.  (For the convenience  of
       aviators, C-INTERCAL accepts the spelling NINER for NINE. In
       the service of internationalization, C-INTERCAL also accepts
       input   digits   in  Sanskrit,  Basque,  Tagalog,  Classical
       Nahuatl, Georgian, Kwakiutl, and Volapuk.)

       Attempting to write in a value greater than or equal to  SIX
       FIVE FIVE THREE SIX for a 16-bit variable will result in the
       error message, "DON'T BYTE OFF MORE THAN YOU CAN CHEW."

       (See also section
        for a description of C-INTERCAL's character I/O.)

       _4_._4_._1_3  _O_u_t_p_u_t

       Values may be output to the printer, one value per line, via
       the  statement  DO  READ  OUT  list, where the list contains
       variables, array elements, and/or constants.  Output  is  in
       the   form   of   "extended"  Roman  numerals  (also  called
       "butchered" Roman numerals), with an overline indicating the
       value  below  is  "times  1000",  and   lower-case   letters
       indicating "times 1000000". Zero is indicated by an overline
       with  no  character  underneath. Thus, the range of (32-bit)
       output values possible is from
       _

       through
       __      ____________
       ivccxcivCMLXVIICCXCV.
       Note: For values whose residues modulo 1000000 are less than
       4000, M is used to represent 1000; for values whose residues
       are 4000 or greater,
       _
       I
       is used. Thus #3999 would read out as  MMMCMXCIX  [3]  while

       






                                  - 24 -



       #4000 would readout as
       __
       IV
       Similar rules apply to the use of
       _
       M
       and i for 1000000, and to that of m and
       _
       i
       for 1000000000.

       (See also section
        for a description of C-INTERCAL's character I/O.)

       _4_._4_._1_4  _C_O_M_E _F_R_O_M

       In  which we try to precisely define a statement that should
       never have been born, but is nevertheless one  of  the  more
       useful statements in INTERCAL.

       _4_._4_._1_4_._1  _B_a_c_k_g_r_o_u_n_d

       The earliest known description of the COME FROM statement in
       the  computing  literature is in [R. L. Clark, "A linguistic
       contribution  to  GOTO-less  programming,"  Commun.  ACM  27
       (1984),  pp.  349-350], part of the famous April Fools issue
       of CACM.  The  subsequent  rush  by  language  designers  to
       include  the statement in their languages was underwhelming,
       one might even say nonexistent.  It  was  therefore  decided
       that  COME  FROM  would  be  an  appropriate  addition to C-
       INTERCAL.

       _4_._4_._1_4_._2  _D_e_s_c_r_i_p_t_i_o_n

       There are two useful ways to visualize  the  action  of  the
       COME FROM statement. The simpler is to see that it acts like
       a  GOTO  when  the program is traced backwards in time. More
       precisely, the statements

       (1)     DO <any statement>
               .
               .
               .
       (2)     DO COME FROM (1)

       should be thought of as being equivalent to



       ____________________

       3. The original INTERCAL-72 manual claimed that #3999 should
          render  as MMMIM, but the C-INTERCAL developers have been
          unable to  find  an  algorithm  that  does  this  and  is
          consistent with the rest of the rules.







                                  - 25 -



       (1)     DO <any statement>
       (2)     DO GOTO (3)
               .
               .
               .
       (3)     DO NOTHING

       if INTERCAL actually had a GOTO statement at all,  which  of
       course it doesn't.

       What  this  boils down to is that the statement DO COME FROM
       (label), anywhere in the program, places a kind of invisible
       trap door immediately after statement (label). Execution  or
       abstention  of  that statement is immediately followed by an
       unconditional jump to the COME FROM,  unless  the  (label)ed
       statement is an executed NEXT, in which case the jump occurs
       if  the  program  attempts  to  RESUME  back  to  that  NEXT
       statement. It is an error for more than  one  COME  FROM  to
       refer to the same (label).

       Modification  of the target statement by ABSTAIN or by the %
       qualifier affects only that statement,  not  the  subsequent
       jump.  Such  modifications to the COME FROM itself, however,
       do affect the jump.  Encountering the  COME  FROM  statement
       itself, rather than its target, has no effect.

       _4_._5  _C_o_m_m_e_n_t_s

       Unrecognizable statements, as noted in section , are flagged
       with  a splat (*) during compilation, and are not considered
       fatal errors unless they are encountered  during  execution,
       at  which  time the statement (as input at compilation time)
       is printed and execution is terminated. This allows  for  an
       interesting  (and,  by necessity, unique) means of including
       comments in an INTERCAL listing. For example, the statement:

       *       PLEASE NOTE THAT THIS LINE HAS NO EFFECT

       will be ignored during execution due to the inclusion of the
       NOT qualifier.  User-supplied error messages are  also  easy
       to implement:

       *       DO SOMETHING ABOUT OVERFLOW IN ;3

       as are certain simple conditional errors:

       * (123) DON'T YOU REALIZE THIS STATEMENT SHOULD ONLY BE ENCOUNTERED
                       ONCE?
               PLEASE REINSTATE (123)

       This  pair of statements will cause an error exit the second
       time they are encountered. Caution!!  The  appearance  of  a
       statement identifier in an intended comment will be taken as
       the  beginning  of  a new statement. Thus, the first comment

       






                                  - 26 -



       example above could not have been:

       *       PLEASE NOTE THAT THIS LINE DOES NOTHING

       The third example, however, is valid, despite the appearance
       of two cases of D-space-O, since INTERCAL  does  not  ignore
       extraneous spaces in statement identifiers.
















































       






                                  - 27 -



       _5_.  _O_U_T_S_I_D_E _C_O_M_M_U_N_I_C_A_T_I_O_N

            She  puzzled  over  this  for  some time, but at last a
            bright thought struck her. "Why, it's  a  Looking-glass
            book,  of  course! And, if I hold it up to a glass, the
            words will all go the right way again."

       In which we  try  to  remedy  the  fact  that,  due  to  I/O
       limitations,  INTERCAL can not even in principle perform the
       same tasks  as  other  languages.  It  is  hoped  that  this
       addition will permit INTERCAL users to waste vast quantities
       of computer time well into the 21st century.

       _5_._1  _M_o_t_i_v_a_t_i_o_n

       One  of  the  goals  of  INTERCAL  was to provide a language
       which,  though  different  from  all  other  languages,   is
       nevertheless  theoretically  capable  of all the same tasks.
       INTERCAL-72  failed  to  accomplish  this  because  its  I/O
       functions  could  not  handle  arbitrary streams of bits, or
       even arbitrary sequences of  characters.  A  language  which
       can't  even send its input directly to its output can hardly
       be considered as capable as other languages.

       _5_._2  _T_u_r_i_n_g _T_e_x_t _M_o_d_e_l

       To remedy this problem, character I/O is now provided  in  a
       form  based  on the "Turing Text" model, originally proposed
       by Jon Blow.  The  C-INTERCAL  programmer  can  access  this
       capability by placing a one-dimensional array in the list of
       items  given  to  a  WRITE  IN  or  READ  OUT  statement. On
       execution of the statement, the elements of the array  will,
       from  first to last, be either loaded from the input or sent
       to the output,  as  appropriate,  in  the  manner  described
       below.  There  is  currently  no  support  for I/O involving
       higher-dimensional arrays, but some form of  graphics  might
       be a possible 2-D interpretation.

       The  heart  of  the  Turing  Text  model  is  the  idea of a
       continuous loop  of  tape  containing,  in  order,  all  the
       characters  in the machine's character set. When a character
       is received by the input routine, the tape is  advanced  the
       appropriate  number  of spaces to bring that character under
       the tape head, and the number of spaces the tape  was  moved
       is the number that is actually seen by the INTERCAL program.
       Another  way  to  say  this  is that the number placed in an
       INTERCAL array is the difference between the character  just
       received  and  the  previous character, modulo the number of
       characters in the machine character set.

       Output works in just the opposite fashion, except  that  the
       characters  being  output  come  from  the other side of the
       tape. From this position the characters on the  tape  appear
       to  be  in  reverse order, and are individually backwards as

       






                                  - 28 -



       well. (We would show you what it looks like,  but  we  don't
       have  a  font  with  backwards  letters available.  Use your
       imagination.) The effect is that a number is taken out of an
       INTERCAL array, subtracted from the last character output --
       i.e., the result of the last subtraction -- and then sent on
       down  the  output  channel.  The  only  catch  is  that  the
       character  as  seen  by  the INTERCAL program is the mirror-
       image of the character as seen by the machine and the  user.
       The  bits  of  the  character are therefore taken in reverse
       order as it is sent to  the  output.   Note  that  this  bit
       reversal  affects  only  the  character  seen by the outside
       world; it does not affect the character stored internally by
       the program, from which  the  next  output  number  will  be
       subtracted.   All subtractions are done modulo the number of
       characters in the character set.

       Two different tapes are used for input and output  to  allow
       for  future  expansion  of  the language to include multiple
       input and output channels. Both tapes start at  character  0
       when  a  program begins execution. On input, when an end-of-
       file marker is reached the number placed in the array is one
       greater than the highest-numbered character on the tape.

       _5_._3  _E_x_a_m_p_l_e _P_r_o_g_r_a_m

       If all this seems terribly complicated, it  should  be  made
       perfectly  clear  by  the  following  example program, which
       simply maps its input to its output (like a simplified  UNIX
       "cat").  It  assumes  that  characters  are 8 bits long, but
       that's fine since the current  version  of  C-INTERCAL  does
       too.  It uses the standard library routines for addition and
       subtraction.

               DO ,1 <- #1
               DO .4 <- #0
               DO .5 <- #0
               DO COME FROM (30)
               DO WRITE IN ,1
               DO .1 <- ,1SUB#1
               DO (10) NEXT
               PLEASE GIVE UP
       (20)    PLEASE RESUME '?.1$#256'~'#256$#256'
       (10)    DO (20) NEXT
               DO FORGET #1
               DO .2 <- .4
               DO (1000) NEXT
               DO .4 <- .3~#255
               DO .3 <- !3~#15'$!3~#240'
               DO .3 <- !3~#15'$!3~#240'
               DO .2 <- !3~#15'$!3~#240'
               DO .1 <- .5
               DO (1010) NEXT
               DO .5 <- .2
               DO ,1SUB#1 <- .3








                                  - 29 -



       (30)    PLEASE READ OUT ,1

       For each number received in the  input  array,  the  program
       first  tests the #256 bit to see if the end of file has been
       reached. If not, the previous input character is  subtracted
       off to obtain the current input character. Then the order of
       the  bits  is  reversed to find out what character should be
       sent to the output, and the result is  subtracted  from  the
       last character sent. Finally, the difference is placed in an
       array  and  given to a READ OUT statement. See?  We told you
       it was simple!












































       






                                  - 30 -



       _6_.  _T_r_i_I_N_T_E_R_C_A_L

            "-- oh dear, how puzzling it all is! I'll try if I know
            all the things I used to know. Let me see:  four  times
            five  is  twelve,  and  four times six is thirteen, and
            four times seven is -- oh dear! I shall  never  get  to
            twenty at that rate!"

       In  which  it  is  revealed  that bitwise operations are too
       ordinary for hard-core INTERCAL programmers, and  extensions
       to  other  bases  are  discussed.  These  are  not, strictly
       speaking, extensions to  INTERCAL  itself,  but  rather  new
       dialects   sharing  most  of  the  features  of  the  parent
       language.

       _6_._1  _M_o_t_i_v_a_t_i_o_n

       INTERCAL is really a pretty sissy language. It tries hard to
       be different, but when you get right down to its roots, what
       do you find?  You find bits, that's what. Plain old ones and
       zeroes, in groups of  16  and  32,  just  like  every  other
       language  you've  ever heard of. And what operations can you
       perform on these bits? The INTERCAL  operators  may  arrange
       and permute them in weird and wonderful ways, but at the bit
       level the operators are the same AND, OR and XOR you've seen
       countless times before.

       Once the prospective INTERCAL programmer masters the unusual
       syntax,  she finds herself working with the familiar Boolean
       operators on perfectly ordinary unsigned integer words. Even
       the constants she uses are familiar. After  all,  who  would
       not  immediately  recognize #65535 and #32768? It may take a
       just a moment more to figure  out  #65280,  and  #21845  and
       #43690  could  be puzzles until she notices that they sum to
       #65535, but basically she's still  on  her  home  turf.  The
       16-bit limit on constants actually works in the programmer's
       favor  by insuring that very long anonymous constants cannot
       appear in INTERCAL programs.  And this is in a language that
       is supposed to be different from any other!

       _6_._2  _A_b_a_n_d_o_n _A_l_l _H_o_p_e_._._.

       Standard  INTERCAL  is  based  on  variables  consisting  of
       ordinary bits and familiar Boolean operations on those bits.
       In  pursuit of uniqueness, it seems appropriate to provide a
       new dialect, otherwise identical to INTERCAL, which  instead
       uses variables consisting of trits, i.e. ternary digits, and
       operators  based  on  tritwise  logical  operations. This is
       intended to be a separate dialect, rather than an  extension
       to  INTERCAL  itself, for a number of reasons. Doing it this
       way  avoids  word-length  conflicts,  does  not  spoil   the
       elegance  of  the  Spartan INTERCAL operator set, and dodges
       the objections of those who  might  feel  it  too  great  an
       alteration  to  the  original  language.  Primarily, though,

       






                                  - 31 -



       giving INTERCAL programmers the ability  to  switch  numeric
       base  at  will  amounts  to excessive functionality. So much
       better that a programmer choose a base  at  the  outset  and
       then  be  forced  to  stick with it for the remainder of the
       program.

       _6_._3  _C_o_m_p_i_l_e_r _O_p_e_r_a_t_i_o_n

       The  same  compiler,  ick,  supports   both   INTERCAL   and
       TriINTERCAL.   This  has the advantage that future bug fixes
       and additions to the  language  not  related  to  arithmetic
       immediately apply to both versions.  The compiler recognizes
       INTERCAL source files by the extension '.i', and TriINTERCAL
       source files by the extension '.3i'. It's as simple as that.
       There  is  no  way to mix INTERCAL and TriINTERCAL source in
       the same program, and it is not always possible to determine
       which dialect a program is written in just by looking at the
       source code.

       _6_._4  _D_a_t_a _T_y_p_e_s

       The two TriINTERCAL data types are 10-trit unsigned integers
       and 20-trit  unsigned  integers.  All  INTERCAL  syntax  for
       distinguishing  data  types  is ported to these new types in
       the obvious way. Small words may contain numbers from #0  to
       #59048;  large  words  may  contain  numbers  from  #0$#0 to
       #59048$#59048. Errors are  signaled  for  constants  greater
       than  #59048  and for attempts to WRITE IN numbers too large
       for a given variable or array element to hold.

       Note that though TriINTERCAL considers  all  numbers  to  be
       unsigned,  nothing prevents the programmer from implementing
       arithmetic operations that treat their operands  as  signed.
       Three's  complement  is  one  obvious  choice,  but balanced
       ternary notation is also a possibility.  This  latter  is  a
       very  pretty and symmetrical system in which all 2 trits are
       treated as if they had the value -1.

       _6_._5  _O_p_e_r_a_t_o_r_s

       The  TriINTERCAL  operators  are  designed  to  inherit  the
       relevant  properties  of the standard INTERCAL operators, so
       that both can be considered as merely different  aspects  of
       the  same Platonic ideal. (Not that the word "ideal" is ever
       particularly  relevant  when   used   in   connection   with
       INTERCAL.)

       _6_._5_._1  _B_i_n_a_r_y _O_p_e_r_a_t_o_r_s _I

       The  binary  operators carry over from the original language
       with only minor changes. The mingle operator ($)  creates  a
       20-trit  word  by  alternating  trits  from  its two 10-trit
       operands.  The  select  operator  (~)  is  a   little   more
       complicated,  since  the  ternary tritmask may contain 0, 1,

       






                                  - 32 -



       and 2 trits. If we observe  that  the  select  operation  on
       binary   operands   amounts   to  a  bitwise  AND  and  some
       rearrangement of bits, it  seems  appropriate  to  base  the
       select  for  ternary  operands  on  a  tritwise  AND  in the
       analogous fashion. We therefore postpone the  definition  of
       select until we know what a tritwise AND looks like.

       _6_._5_._2  _U_n_a_r_y _O_p_e_r_a_t_o_r_s

       The  unary  operators  in  INTERCAL are all derived from the
       familiar Boolean operations on single bits. To extend  these
       operations  to  trits,  we  first  ask  ourselves  what  the
       important properties of these operations are that we wish to
       be preserved, then design the  tritwise  operators  so  that
       they behave in a similar fashion.

       _6_._5_._2_._1  _U_n_a_r_y _L_o_g_i_c_a_l _O_p_e_r_a_t_o_r_s

       Let's  start  with  AND  and OR. To begin with, these can be
       considered  "choice"  or  "preference"  operators,  as  they
       always return one of their operands. AND can be described as
       wanting to return 0, but returning 1 if it is given no other
       choice, i.e., if both operands are 1. Similarly, OR wants to
       return 1 but returns 0 if that is its only choice. From this
       it  is  immediately  apparent  that  each  operator  has  an
       identity  element  that  "always  loses",  and  a  dominator
       element that "always wins".

       AND  and  OR  are  commutative  and  associative,  and  each
       distributes over the other. They  are  also  symmetric  with
       each other, in the sense that AND looks like OR and OR looks
       like  AND  when  the  roles  of 0 and 1 are interchanged (De
       Morgan's Laws). This symmetry property seems  to  be  a  key
       element  to  the  idea  that  these are logical, rather than
       arithmetic, operators. In  a  three-valued  logic  we  would
       similarly expect a three-way symmetry among the three values
       0,  1  and 2 and the three operators AND, OR and (of course)
       BUT.

       The following  tritwise  operations  have  all  the  desired
       properties: OR returns the greater of its two operands. That
       is,  it  returns 2 if it can get it, else it tries to return
       1, and it returns 0 only if both operands are 0.  AND  wants
       to  return 0, will return 2 if it can't get 0, and returns 1
       only if forced. BUT wants 1, will take 0, and tries to avoid
       2. The equivalents to De Morgan's Laws apply to rotations of
       the three elements, e.g., 0 -> 1, 1  ->  2,  2  ->  0.  Each
       operator distributes over exactly one other operator, so the
       property  "X  distributes  over  Y"  is  not transitive. The
       question of which way this distributivity ring  goes  around
       is left as an exercise for the student.

       In  TriINTERCAL programs the whirlpool (@) denotes the unary
       tritwise BUT operation. You can think of  the  whirlpool  as

       






                                  - 33 -



       drawing  values  preferentially towards the central value 1.
       Alternatively, you can think of it as drawing your soul  and
       your sanity inexorably down ...

       On  the other hand, maybe it's best you _n_o_t think of it that
       way.

       A few comments about how these operators  can  be  used.  OR
       acts like a tritwise maximum operation. AND can be used with
       tritmasks. 0's in a mask wipe out the corresponding elements
       in  the  other  operand,  while  1's  let  the corresponding
       elements pass through unchanged. 2's in a  mask  consolidate
       the  values  of nonzero elements, as both 1's and 2's in the
       other operand yield 2's in the output. BUT can  be  used  to
       create  "partial tritmasks". 0's in a mask let BUT eliminate
       2's from  the  other  operand  while  leaving  other  values
       unchanged.  Of course, the symmetry property guarantees that
       the operators don't  really  behave  differently  from  each
       other  in any fundamental way; the apparent differences come
       from the intuitive view that a 0 trit is "not set" while a 1
       or 2 trit is "set".

       _6_._5_._2_._2  _B_i_n_a_r_y _O_p_e_r_a_t_o_r_s _I_I

       At this point we can define select, since we now  know  what
       the  tritwise  AND  looks  like.  Select  takes  the  binary
       tritwise AND of its two operands. It shifts all the trits of
       the result corresponding to 2's in the right operand over to
       the right (low) end of the result, then  follows  them  with
       all  the  output  trits  corresponding  to  1's in the right
       operand. Trits corresponding to 0's in  the  right  operand,
       which  are  all  0 anyway, occupy the remaining space at the
       left end of  the  output  word.  Both  10-trit  and  20-trit
       operands  are  accepted,  and  are padded with zeroes on the
       left if necessary. The output type is  determined  the  same
       way as in standard C-INTERCAL.

       _6_._5_._2_._3  _U_n_a_r_y _A_r_i_t_h_m_e_t_i_c _O_p_e_r_a_t_o_r_s

       Now that we've got all that settled, what about XOR? This is
       easily   the   most-useful   of  the  three  unary  INTERCAL
       operators, because it combines in one package the operations
       ADD WITHOUT CARRY, SUBTRACT  WITHOUT  BORROW,  BITWISE  NOT-
       EQUAL,  and BITWISE NOT. In TriINTERCAL we can't have all of
       these in the same operator, since addition  and  subtraction
       are  no  longer the same thing. The solution is to split the
       XOR concept  into  two  operators.  The  ADD  WITHOUT  CARRY
       operation  is represented by the new sharkfin (^), while the
       old what (?) represents SUBTRACT WITHOUT BORROW. The  reason
       for  this choice is so that what (?) will also represent the
       TRITWISE NOT-EQUAL operation.

       Note that what (?), unlike the other four  unary  operators,
       is  not symmetrical. It should be thought of as rotating its

       






                                  - 34 -



       operand one trit to the right  (with  wraparound)  and  then
       subtracting  off  the  trits  of  the original number. These
       subtractions are done without borrowing, i.e.,  trit-by-trit
       modulo 3.

       _6_._5_._3  _E_x_a_m_p_l_e_s

       The  TriINTERCAL  operators  really aren't all that bad once
       you get used to them. Let's look at a few examples  to  show
       how  they  can be used in practice. In all of these examples
       the input value is contained in the 10-trit variable .3.

       In INTERCAL, single-bit values often have  to  be  converted
       from  {0,1}  to {1,2} for use in RESUME statements. Examples
       of how  to  do  this  appear  in  the  original  manual.  In
       TriINTERCAL the expression "^.3$#1"~#1 sends 0 -> 1 and 1 ->
       2.  If  the  1-trit input value can take on any of its three
       possible states, however, we will also have to deal with the
       2 case. The expression "V.3$#1"~#1 sends {0,1} -> 1 and 2 ->
       2.   To   test   if   a   trit   is   set,   we   can    use
       "V'"&.3$#2"~#1'$#1"~#1,  sending  0  -> 1 and {1,2} -> 2. To
       reverse the test we use "?'"&.3$#2"~#1'$#1"~#1, sending 0 ->
       2 and {1,2} -> 1. Note that we have  not  been  taking  full
       advantage  of  the  new  select  operator.  These  last  two
       expressions  can  be  simplified  into  "V!3~#2'$#1"~#1  and
       "?!3~#2'$#1"~#1,  which  perform  exactly the same mappings.
       Finally,  if  we   need   a   3-way   test,   we   can   use
       "@'"^.3$#7"~#4'$#2"~#10,  which obviously sends 0 -> 1, 1 ->
       2, and 2 -> 3.

       For     an     unrelated     example,     the     expression
       "^.3$.3"~"#0$#29524"  converts all of the 1-trits of .3 into
       2's and all of the 2-trits into 1's.  In  balanced  ternary,
       where  2-trits  represent  -1  values,  this is the negation
       operation.

       _6_._6  _B_e_y_o_n_d _T_e_r_n_a_r_y_._._.

       While we're at it, we might as  well  extend  this  multiple
       bases  business  a little farther. The ick compiler actually
       recognizes filename suffixes of the form '.Ni', where  N  is
       any number from 2 to 7. 2 of course gives standard INTERCAL,
       while  3  gives  TriINTERCAL.   We  cut off before 8 because
       octal notation is  the  smallest  base  used  to  facilitate
       human-to-machine   communication,   and   this  seems  quite
       contrary to the basic principles behind INTERCAL. The  small
       data  types  hold  16  bits, 10 trits, 8 quarts, 6 quints, 6
       sexts, or 5 septs, and the large types are always twice this
       size.

       As for operators, ? is always SUBTRACT WITHOUT BORROW, and ^
       is always ADD WITHOUT CARRY.  V  is  the  OR  operation  and
       always  returns  the  max  of  its  inputs.  &  is  the  AND
       operation, which chooses 0 if possible but otherwise returns

       






                                  - 35 -



       the max of the inputs. @ is BUT, which prefers  1,  then  0,
       then  the  max  of the remaining possibilities.  Rather than
       add more special symbols forever, a numeric modifier may  be
       placed  directly before the @ to indicate the operation that
       prefers one of the digits not already represented.  Thus  in
       files  ending in '.5i', the permitted unary operators are ?,
       ^, &, @, 2@, 3@, and V. Use of  such  barbarisms  as  0@  to
       represent  &  are not permitted, nor is the use of @ or ^ in
       files with either of the extensions '.i' or '.2i'. Why  not?
       You just can't, that's why.  Don't ask so many questions.

       As  a  closing  example,  we  note  that in balanced quinary
       notation, where 3 means -2 and  4  means  -1,  the  negation
       operation can be written as either

         DO .1 <- "^'"^.3$.3"~"#0$#3906"'$'"^.3$.3"~"#0$#3906"'"~"#0$#3906"

       or as

         DO .1 <- "^.3$.3"~"#0$#3906"
         DO .1 <- "^.1$.1"~"#0$#3906"

       These  work  because  multiplication  by  -1  is the same as
       multiplication by 4, modulo 5.

       Now go beat your head against the wall for a while.





























       






                                  - 36 -



       _7_.  _S_U_B_R_O_U_T_I_N_E _L_I_B_R_A_R_Y

            "You don't  know  what  you're  talking  about!"  cried
            Humpty Dumpty. "How many days are there in a year?"

            "Three hundred and sixty-five," said Alice.

            "And how many birthdays have you?"

            "One."

            "And if you take one from three hundred and sixty-five,
            what remains?"

            "Three hundred and sixty-four, of course."

            Humpty  Dumpty  looked  doubtful.  "I'd rather see that
            done on paper," he said.

       INTERCAL provides  several  built-in  subroutines  to  which
       control  can  be  transferred to perform various operations.
       These operations include many useful functions which are not
       easily  representable  in  INTERCAL,   such   as   addition,
       subtraction, etc.

       _7_._1  _U_s_a_g_e

       In  general, the operands are .1, .2, etc., or :1, :2, etc.,
       and the result(s) are stored in what  would  have  been  the
       next operand(s). For instance, one routine adds .1 to .2 and
       stores  the  sum  in  .3,  with  .4  being  used to indicate
       overflow. All  variables  not  used  for  results  are  left
       unchanged.

       _7_._2  _A_v_a_i_l_a_b_l_e _F_u_n_c_t_i_o_n_s

       At  the  time  of  this  writing,  only the most fundamental
       operations are offered in the library, as  a  more  complete
       selection   would  require  prohibitive  time  and  core  to
       implement. These functions, along with  their  corresponding
       entry points (entered via DO (entry) NEXT) are listed below.














       






                                  - 37 -



        (1000) .3 <- .1 plus .2, error exit on overflow
        (1009) .3 <- .1 plus .2
               .4 <- #1 if no overflow, else .4 <- #2
        (1010) .3 <- .1 minus .2, no action on overflow
        (1020) .1 <- .1 plus #1, no action on overflow
        (1030) .3 <- .1 times .2, error exit on overflow
        (1039) .3 <- .1 times .2
               .4 <- #1 if no overflow, else .4 <- #2
        (1040) .3 <- .1 divided by .2
               .3 <- #0 if .2 is #0
        (1050) .2 <- :1 divided by .1, error exit on overflow
               .2 <- #0 if .1 is #0

        (1500) :3 <- :1 plus :2, error exit on overflow
        (1509) :3 <- :1 plus :2
               :4 <- #1 if no overflow, else :4 <- #2
        (1510) :3 <- :1 minus :2, no action on overflow
        (1520) :1 <- .1 concatenated with .2
        (1525) This subroutine is intended solely for internal
               use within the subroutine library and is therefore
               not described here. Its effect is to shift .3
               logically 8 bits to the left.
        (1530) :1 <- .1 times .2
        (1540) :3 <- :1 times :2, error exit on overflow
        (1549) :3 <- :1 times :2
               :4 <- #1 if no overflow, else :4 <- #2
        (1550) :3 <- :1 divided by :2
               :3 <- #0 if :2 is #0

        (1900) .1 <- uniform random no. from #0 to #65535
        (1910) .2 <- normal random no. from #0 to .1, with
                     standard deviation .1 divided by #12

       _7_._3  _A_u_t_o_m_a_g_i_c_a_l _I_n_c_l_u_s_i_o_n _O_f _T_h_e _S_u_b_r_o_u_t_i_n_e _L_i_b_r_a_r_y

       The  C-INTERCAL  compiler  will  automatically  include  the
       system library if a DO (1xxx) NEXT statement is used, and if
       no (1xxx) labels are defined anywhere,  where  (1xxx)  is  a
       label  in  the  1000-1999  range, inclusive. This was not an
       INTERCAL-72 feature.















       






                                  - 38 -



       _8_.  _P_R_O_G_R_A_M_M_I_N_G _H_I_N_T_S

            "If any one of them can explain it," said Alice,  "I'll
            give  him  sixpence. _I don't believe there's an atom of
            meaning in it."  The jury  all  wrote  down,  on  their
            slates, "_S_h_e doesn't believe there's an atom of meaning
            in  it,"  but  none  of  them  attempted to explain the
            paper.

            "If there's no meaning in it,"  said  the  King,  "that
            saves  a  world of trouble, you know, as we needn't try
            to find any. And  yet,  I  don't  know,"  he  went  on,
            spreading  out  the  verses on one knee, and looking at
            them with one eye: "I seem to see some meaning in them,
            after all...."

       For the user  looking  to  become  more  familiar  with  the
       INTERCAL language, we present in this section an analysis of
       a  complex  program,  as well as some suggested projects for
       the ambitious programmer.

       Considering the  effort  involved  in  writing  an  INTERCAL
       program,  it  was decided in putting together this manual to
       use an already existing program  for  instructive  analysis.
       Since  there  was  only  one such program available, we have
       proceeded to use it. It is known  as  the  "INTERCAL  System
       Library."

       _8_._1  _D_e_s_c_r_i_p_t_i_o_n

       The program listing is in section . It is in the same format
       as  would  be produced by the Princeton INTERCAL compiler in
       FORMAT mode with WIDTH=62 (see section ). For a  description
       of the functions performed by the Library, see section .

       _8_._2  _A_n_a_l_y_s_i_s

       We  shall  not  attempt to discuss here the algorithms used,
       but rather we shall point out some of the general techniques
       applicable to a wide range of problems.

       Statements 10, 14, 15, and 26 make up a virtual "computed GO
       TO".  When  statement  10  is   executed,   control   passes
       eventually  to  statement  16 or 11, depending on whether .5
       contains  #1  or  #2,  respectively.  The  value  of  .5  is
       determined  in statement 9, which demonstrates another handy
       technique.  To turn an expression, exp, with value #0 or #1,
       into #1 or #2 (for use in a "GO  TO"),  use  "V-'exp'c/#1"~#3.
       To  reverse  the condition (i.e., convert #0 to #2 and leave
       #1 alone) use "V-'exp'c/#2"~#3.

       Certain conditions are easily checked. For example, to  test
       for zero, select the value from itself and select the bottom
       bit  (see  statement  54).   To test for all bits being 1's,

       






                                  - 39 -



       select the value from itself and select the  top  bit.   The
       test  for  greater than, performed in statements 219 and 220
       on 32-bit values, employs binary logical  operations,  which
       are performed as follows:

       'V-.1c/.2'~'#0c/#65535'

       for 16-bit values or, for 32-bit values:

               "'V-":1~'#65535c/30'"c/":2~'#65535c/#0'"'~'#0
               c/#65535'"c/"'V-":1~'#0c/#65535'"c/":2~'#0
               c/#65535'"'~'#0c/#65535'"

       (The proofs are left as an exercise to the reader.)

       Testing  for  greater-than  with  16-bit  values is somewhat
       simpler and is done with the pair of statements:

               DO .C <- 'V-.Ac/.B'~'#0c/#65535'
               DO .C <- '&"'.A~.C'~'"V-'V-.C~.C'c/#32768"
                       ~"#0c/#65535"'"c/".C~.C"'~#1

       This sets .C (a dummy variable) to #1 if .A  >  .B,  and  #0
       otherwise. The expression may be expanded as described above
       to instead set .C to #1 or #2.

       Note    also    in   statement   220   the   occurrence   of
       ~"#65535c/#65535".  Although  these  operations  select   the
       entire  value,  they are not extraneous, as they ensure that
       the forthcoming V-s will be operating on 32-bit values.

       In  several  virtual  computed  GO  TOs  the  DO  FORGET  #1
       (statement  15  in  the  earlier  example) has been omitted,
       since the next transfer of control would be a DO RESUME  #1.
       By  making  this  a  DO RESUME #2 instead, the FORGET may be
       forgotten.

       In statement 64, note that .2 is STASHed twice by  a  single
       statement. This is perfectly legal.

       Lastly,   note  in  statements  243  and  214  respectively,
       expressions for shifting 16- and 32-bit variables  logically
       one  place  to  the left.  Statement 231 demonstrates right-
       shifting for 32-bit variables.











       






                                  - 40 -



       _8_._3  _P_r_o_g_r_a_m _L_i_s_t_i_n_g






















































       






                                  - 41 -



            1          (1000)  PLEASE IGNORE .4
            2                  PLEASE ABSTAIN FROM (1005)
            3          (1009)  DO STASH .1 + .2 + .5 + .6
            4                  DO .4 <- #1
            5                  DO (1004) NEXT
            6          (1004)  PLEASE FORGET #1
            7                  DO .3 <- 'V-.1c/.2'~'#0c/#65535'
            8                  DO .6 <- '&.1c/.2'~'#0c/#65535'
            9                  PLEASE DO .5 <- "V-!6~#32768'c/#1"~#3
           10                  DO (1002) NEXT
           11                  DO .4 <- #2
           12          (1005)  DO (1006) NEXT
       *   13          (1999)  DOUBLE OR SINGLE PRECISION OVERFLOW
           14          (1002)  DO (1001) NEXT
           15          (1006)  PLEASE FORGET #1
           16                  DO .5 <- 'V-"!6~.6'~#1"c/#1'~#3
           17                  DO (1003) NEXT
           18                  DO .1 <- .3
           19                  DO .2 <- !6c/#0'~'#32767c/#1'
           20                  DO (1004) NEXT
           21          (1003)  DO (1001) NEXT
           22                  DO REINSTATE (1005)
           23          (1007)  PLEASE RETRIEVE .1 + .2 + .5 + .6
           24                  DO REMEMBER .4
           25                  PLEASE RESUME #2
           26          (1001)  DO RESUME .5
           27          (1010)  DO STASH .1 + .2 + .4
           28                  DO .4 <- .1
           29                  DO .1 <- 'V-.2c/#65535'~'#0c/#65535'
           30                  DO (1020) NEXT
           31                  PLEASE DO .2 <- .4
           32                  PLEASE DO (1009) NEXT
           33                  DO RETRIEVE .1 + .2 + .4
           34                  PLEASE RESUME #1
           35          (1020)  DO STASH .2 + .3
           36                  DO .2 <- #1
           37                  PLEASE DO (1021) NEXT
           38          (1021)  DO FORGET #1
           39                  DO .3 <- "V-!1~.2'c/#1"~#3
           40                  PLEASE DO .1 <- 'V-.1c/.2'~'#0c/#65535'
           41                  DO (1022) NEXT
           42                  DO .2 <- !2c/#0'~'#32767c/#1'
           43                  DO (1021) NEXT
           44          (1023)  PLEASE RESUME .3
           45          (1022)  DO (1023) NEXT
           46                  PLEASE RETRIEVE .2 + .3
           47                  PLEASE RESUME #2
           48          (1030)  DO ABSTAIN FROM (1033)
           49                  PLEASE ABSTAIN FROM (1032)
           50          (1039)  DO STASH :1 + .5
           51                  DO (1530) NEXT
           52                  DO .3 <- :1~#65535
           53                  PLEASE DO .5 <- :1~'#65280c/#65280'
           54                  DO .5 <- 'V-"!5~.5'~#1"c/#1'~#3








                                  - 42 -



           55                  DO (1031) NEXT
           56          (1032)  DO (1033) NEXT
           57                  DO (1999) NEXT
           58          (1031)  DO (1001) NEXT
           59          (1033)  DO .4 <- .5
           60                  DO REINSTATE (1032)
           61                  PLEASE REINSTATE (1033)
           62                  DO RETRIEVE :1 + .5
           63                  PLEASE RESUME #2
           64          (1040)  PLEASE STASH .1 + .2 + .2 + :1 + :2 + :3
           65                  DO .2 <- #0
           66                  DO (1520) NEXT
           67                  DO STASH :1
           68                  PLEASE RETRIEVE .2
           69                  DO .1 <- .2
           70                  DO .2 <- #0
           71                  PLEASE DO (1520) NEXT
           72                  DO :2 <- :1
           73                  DO RETRIEVE .1 + .2 + :1
           74                  DO (1550) NEXT
           75                  PLEASE DO .3 <- :3
           76                  DO RETRIEVE :1 + :2 + :3
           77                  DO RESUME #1
           78          (1050)  PLEASE STASH :2 + :3 + .5
           79                  DO :2 <- .1
           80                  PLEASE DO (1550) NEXT
           81                  DO .5 <- :3~'#65280c/#65280'
           82                  DO .5 <- 'V-"!5~.5'~#1"c/#1'~#3
           83                  DO (1051) NEXT
           84                  DO (1999) NEXT
           85          (1051)  DO (1001) NEXT
           86                  DO .2 <- :3
           87                  PLEASE RETRIEVE :2 + :3 + .5
           88                  DO RESUME #2
           89          (1500)  PLEASE ABSTAIN FROM (1502)
           90                  PLEASE ABSTAIN FROM (1506)
           91          (1509)  PLEASE STASH :1 + .1 + .2 + .3 + .4 + .5 + .6
           92                  DO .1 <- :1~#65535
           93                  PLEASE DO .2 <- :2~#65535
           94                  DO (1009) NEXT
           95                  DO .5 <- .3
           96                  PLEASE DO .6 <- .4
           97                  DO .1 <- :1~'#65280c/#65280'
           98                  DO .2 <- :2~'#65280c/#65280'
           99                  DO (1009) NEXT
          100                  DO .1 <- .3
          101                  PLEASE DO (1503) NEXT
          102                  DO .6 <- .4
          103                  DO .2 <- #1
          104                  DO (1009) NEXT
          105                  DO .1 <- .3
          106                  DO (1501) NEXT
          107          (1504)  PLEASE RESUME .6
          108          (1503)  DO (1504) NEXT








                                  - 43 -



          109          (1501)  DO .2 <- .5
          110                  DO .5 <- 'V-"'&.6c/.4'~#1"c/#2'~#3
          111                  DO (1505) NEXT
          112          (1506)  DO (1502) NEXT
          113                  PLEASE DO (1999) NEXT
          114          (1505)  DO (1001) NEXT
          115          (1502)  DO :4 <- .5
          116                  DO (1520) NEXT
          117                  DO :3 <- :1
          118                  PLEASE RETRIEVE :1 + .1 + .2 + .3 + .4 + .5 + .6
          119                  DO REINSTATE (1502)
          120                  DO REINSTATE (1506)
          121                  PLEASE RESUME #3
          122          (1510)  DO STASH :1 + :2 + :4
          123                  DO :1 <- "'V-":2~'#65535c/#0'"c/#65535'
                                   ~'#0c/#65535'"c/"'V-":2~'#0c/#65535'
                                   "c/#65535'~'#0c/#65535'"
          124                  DO :2 <- #1
          125                  DO (1509) NEXT
          126                  PLEASE RETRIEVE :1
          127                  DO :2 <- :3
          128                  PLEASE DO (1509) NEXT
          129                  DO RETRIEVE :2 + :4
          130                  PLEASE RESUME #1
          131          (1520)  PLEASE STASH .3 + .4
          132                  DO .3 <- .1~#43690
          133                  DO (1525) NEXT
          134                  PLEASE DO .4 <- 'V.3c/".2~#43690"'~'#0c/#65535'
          135                  DO .3 <- .1~#21845
          136                  PLEASE DO (1525) NEXT
          137                  DO :1 <- .4c/"'V.3c/".2~#21845"'~'#0c/#65535'"
          138                  PLEASE RETRIEVE .3 + .4
          139                  DO RESUME #1
          140          (1525)  DO .3 <- '"'"'"!3c/#0'~'#32767c/#1'"c/#0'
                                   ~'#32767c/#1'"c/#0'~'#16383c/#3'"c/#0'
                                   ~'#4095c/#15'
          141                  PLEASE RESUME #1
          142          (1530)  DO STASH :2 + :3 + .3 + .5
          143                  DO :1 <- #0
          144                  DO :2 <- .2
          145                  DO .3 <- #1
          146                  DO (1535) NEXT
          147          (1535)  PLEASE FORGET #1
          148                  DO .5 <- "V-!1~.3'c/#1"~#3
          149                  DO (1531) NEXT
          150                  DO (1500) NEXT
          151                  DO :1 <- :3
          152                  PLEASE DO (1533) NEXT
          153          (1531)  PLEASE DO (1001) NEXT
          154          (1533)  DO FORGET #1
          155                  DO .3 <- !3c/#0'~'#32767c/#1'
          156                  DO :2 <- ":2~'#0c/#65535'"c/"'":2~'#32767
                                   c/#0'"c/#0'~'#32767c/#1'"
          157                  PLEASE DO .5 <- "V-!3~.3'c/#1"~#3








                                  - 44 -



          158                  DO (1532) NEXT
          159                  DO (1535) NEXT
          160          (1532)  DO (1001) NEXT
          161                  PLEASE RETRIEVE :2 + :3 + .3 + .5
          162                  DO RESUME #2
          163          (1540)  PLEASE ABSTAIN FROM (1541)
          164                  DO ABSTAIN FROM (1542)
          165          (1549)  PLEASE STASH :1 + :2 + :4 + :5 + .1 + .2 + .5
          166                  DO .1 <- :1~#65535
          167                  PLEASE DO .2 <- :2~'#65280c/#65280'
          168                  DO .5 <- :1~'#65280c/#65280'
          169                  DO (1530) NEXT
          170                  DO :3 <- :1
          171                  DO .2 <- :2~#65535
          172                  PLEASE DO (1530) NEXT
          173                  DO :5 <- :1
          174                  DO .1 <- .5
          175                  DO (1530) NEXT
          176                  DO :4 <- :1
          177                  PLEASE DO :1 <- ":3~'#65280c/#65280'"
                                   c/":4~'#65280c/#65280'"
          178                  DO .5 <- ':1~:1'~#1
          179                  DO .2 <- :2~'#65280c/#65280'
          180                  DO (1530) NEXT
          181                  PLEASE DO .5 <- '"':1~:1'~#1"c/.5'~#3
          182                  DO .1 <- :3~#65535
          183                  DO .2 <- #0
          184                  DO (1520) NEXT
          185                  PLEASE DO :2 <- :1
          186                  PLEASE DO .1 <- :4~#65535
          187                  DO (1520) NEXT
          188                  DO (1509) NEXT
          189                  DO .5 <- !5c/":4~#3"'~#15
          190                  DO :1 <- :3
          191                  DO :2 <- :5
          192                  DO (1509) NEXT
          193                  PLEASE DO .5 <- !5c/":4~#3"'~#172
          194                  DO .5 <- 'V-"!5~.5'~#1"c/#1'~#3
          195                  PLEASE RETRIEVE :4
          196          (1541)  DO :4 <- .5
          197                  DO (1543) NEXT
          198          (1542)  DO (1544) NEXT
          199                  PLEASE DO (1999) NEXT
          200          (1543)  DO (1001) NEXT
          201          (1544)  DO REINSTATE (1541)
          202                  PLEASE REINSTATE (1542)
          203                  PLEASE RETRIEVE :1 + :2 + :5 + .1 + .2 + .5
          204                  DO RESUME #2
          205          (1550)  DO STASH :1 + :4 + :5 + .5
          206                  DO :3 <- #0
          207                  DO .5 <- 'V-"':2~:2'~#1"c/#1'~#3
          208                  PLEASE DO (1551) NEXT
          209                  DO :4 <- #1
          210                  PLEASE DO (1553) NEXT








                                  - 45 -



          211          (1553)  DO FORGET #1
          212                  DO .5 <- 'V-":2~'#32768c/#0'"c/#2'~#3
          213                  DO (1552) NEXT
          214                  DO :2 <- ":2~'#0c/#65535'"c/"'":2~'#32767
                                   c/#0'"c/#0'~'#32767c/#1'"
          215                  PLEASE DO :4 <- ":4~'#0c/#65535'"c/"'":4
                                   ~'#32767c/#0'"c/#0'~'#32767c/#1'"
          216                  DO (1553) NEXT
          217          (1552)  DO (1001) NEXT
          218          (1556)  PLEASE FORGET #1
          219                  DO :5 <- "'V-":1~'#65535c/#0'"c/":2
                                   ~'#65535c/#0'"'~'#0c/#65535'"c/"'
                                   V-":1~'#0c/#65535'"c/":2~'#0c/
                                   #65535'"'~'#0c/#65535'"
          220                  DO .5 <- 'V-"'&"':2~:5'~'"'V-"'V-":5~:5
                                   "~"#65535c/#65535"'~'#65535c/#0'"c/
                                   #32768'~'#0c/#65535'"c/"'V-":5~:5"
                                   ~"#65535c/#65535"'~'#0c/#65535'"'"c/"'
                                   :5~:5'~#1"'~#1"c/#2'~#3
          221                  DO (1554) NEXT
          222                  DO :5 <- :3
          223                  DO (1510) NEXT
          224                  PLEASE DO :1 <- :3
          225                  DO :3 <- "'V":4~'#65535c/#0'"c/":5~'#65535
                                   c/#0'"'~'#0c/#65535'"c/"'V":4~'#0
                                   c/#65535'"c/":5~'#0c/#65535'"'~'#0
                                   c/#65535'"
          226                  DO (1555) NEXT
          227          (1554)  PLEASE DO (1001) NEXT
          228          (1555)  DO FORGET #1
          229                  DO .5 <- "V-':4~#1'c/#2"~#3
          230                  DO (1551) NEXT
          231                  DO :2 <- ":2~'#0c/#65534'"c/":2~'#65535c/#0'"
          232                  DO :4 <- ":4~'#0c/#65534'"c/":4~'#65535c/#0'"
          233                  PLEASE DO (1556) NEXT
          234          (1551)  DO (1001) NEXT
          235                  PLEASE RETRIEVE :1 + :4 + :5 + .5
          236                  PLEASE RESUME #2
          237          (1900)  DO STASH .2 + .3 + .5
          238                  DO .1 <- #0
          239                  DO .2 <- #1
          240                  PLEASE DO (1901) NEXT
          241          (1901)  DO FORGET #1
          242                  DO %50 .1 <- 'V.1c/.2'~'#0c/#65535'
          243                  DO .2 <- !2c/#0'~'#32767c/#1'
          244                  PLEASE DO .5 <- "V-!2~.2'c/#1"~#3
          245                  DO (1902) NEXT
          246                  DO (1901) NEXT
          247          (1902)  DO (1001) NEXT
          248                  DO RETRIEVE .2 + .3 + .5
          249                  PLEASE RESUME #2
          250          (1910)  PLEASE STASH .1 + .3 + .5 + :1 + :2 + :3
          251                  DO .3 <- #65524
          252                  DO :1 <- #6








                                  - 46 -



          253                  DO (1911) NEXT
       *  254                  PLEASE NOTE THAT YOU CAN'T GET THERE FROM HERE
          255          (1912)  DO (1001) NEXT
          256          (1911)  DO FORGET #1
          257                  PLEASE DO (1900) NEXT
          258                  DO :2 <- .1
          259                  DO (1500) NEXT
          260                  PLEASE DO :1 <- :3
          261                  DO .1 <- .3
          262                  DO (1020) NEXT
          263                  PLEASE DO .3 <- .1
          264                  DO .5 <- 'V-"!3~.3'~#1"c/#2'~#3
          265                  DO (1912) NEXT
          266                  DO .1 <- #12
          267                  PLEASE DO (1050) NEXT
          268                  DO RETRIEVE .1
          269                  DO (1530) NEXT
          270                  DO :2 <- #32768
          271                  DO (1500) NEXT
          272                  PLEASE DO .2 <- :3~'#65280c/#65280'
          273                  PLEASE RETRIEVE .3 + .5 + :1 + :2 + :3
          274                  DO RESUME #1








































                                  - 47 -



       _8_._4  _P_r_o_g_r_a_m_m_i_n_g _S_u_g_g_e_s_t_i_o_n_s

       For the novice INTERCAL programmer, we provide here  a  list
       of suggested INTERCAL programming projects:

       Write an integer exponentiation subroutine.  :1 <- .1 raised
       to the .2 power.

       Write  a  double-precision  sorting subroutine. Given 32-bit
       array ;1 of size :1,  sort  the  contents  into  numerically
       increasing order, leaving the results in ;1.

       Generate a table of prime numbers.

       Put   together   a   floating-point  library,  using  32-bit
       variables to represent floating-point numbers (let the upper
       half  be  the  mantissa  and   the   lower   half   be   the
       characteristic).    The   library   should   be  capable  of
       performing     floating-point     addition,     subtraction,
       multiplication,   and  division,  as  well  as  the  natural
       logarithm function.

       Program a Fast Fourier Transform (FFT).  This project  would
       probably entail the writing of the floating-point library as
       well as sine and cosine functions.

       Calculate, to :1 places, the value of pi.

       (Working programs for each of these projects are included in
       the C-INTERCAL distribution's pit directory of sample code.)

























       






                                  - 48 -



       _9_.  _E_R_R_O_R _M_E_S_S_A_G_E_S

            Alice  felt  dreadfully  puzzled.  The  Hatter's remark
            seemed to her to have no sort of meaning in it, and yet
            it was certainly English.  "I  don't  quite  understand
            you," she said, as politely as she could.

       Due  to  INTERCAL's  implementation  of  comment  lines (see
       section  4.5),  most  error  messages  are  produced  during
       execution  instead of during compilation.  All errors except
       those not causing immediate termination of program execution
       are treated as fatal.

       _9_._1  _F_o_r_m_a_t

       All error messages appear in the following form:

               ICLnnnI (error message)
                       ON THE WAY TO STATEMENT nnnn
                       CORRECT SOURCE AND RESUBMIT

       The message varies depending upon the error  involved.   For
       undecodable  statements the message is the statement itself.
       The second  line  tells  which  statement  would  have  been
       executed  next had the error not occurred.  Note that if the
       error  is  due  to  80  attempted  levels  of  NEXTing,  the
       statement  which  would  have been executed next need not be
       anywhere near the statement causing the error.

       _9_._2  _M_e_s_s_a_g_e_s

       Brief descriptions of the different error types  are  listed
       below according to message number.

        000 An  undecodable  statement  has been encountered in the
            course of execution. Note that keypunching  errors  can
            be   slightly   disastrous,   since  if  'FORGET'  were
            misspelled F-O-R-G-E-R, the results would probably  not
            be  those  desired.  Extreme misspellings may have even
            more surprising consequences. For example,  misspelling
            'FORGET' R-E-S-U-M-E could have drastic results.

        017 An expression contains a syntax error.

        079 Improper use has been made of statement identifiers.

        099 Improper use has been made of statement identifiers.

        123 Program has attempted 80 levels of NEXTing.

        129 Program  has  attempted  to  transfer to a non-existent
            line label.



       






                                  - 49 -



        139 An ABSTAIN or REINSTATE  statement  references  a  non-
            existent line label.

        182 A line label has been multiply defined.

        197 An invalid line label has been encountered.

        200 An expression involves an unidentified variable.

        240 An  attempt  has been made to give an array a dimension
            of zero.

        241 Invalid  dimensioning  information  was   supplied   in
            defining or using an array.

        275 A 32-bit value has been assigned to a 16-bit variable.

        436 A retrieval has been attempted for an unSTASHed value.

        533 A  WRITE  IN  statement or interleave (c/) operation has
            produced a value requiring over 32 bits to represent.

        562 Insufficient data.

        579 Input data is invalid.

        621 The expression of a RESUME statement evaluated to #0.

        632 Program execution was terminated via a RESUME statement
            instead of GIVE UP.

        633 Execution has passed beyond the last statement  of  the
            program.

        774 A compiler error has occurred (see section ).

        778 An unexplainable compiler error has occurred.

       The following error codes are new in C-INTERCAL:

        111 You  tried  to  use  a  C-INTERCAL  extension  with the
            `traditional' flag on.

        127 Can't find syslib.i file when it's needed  for  magical
            inclusion.

        222 Out  of  stash space, or attempt to stash an undeclared
            array.

        333 Too many variables.

        444 A COME FROM statement references  a  non-existent  line
            label.


       






                                  - 50 -



        555 More than one COME FROM references the same label.

        666 Too many source lines.

        777 No such source file.

        888 Can't open C output file.

        999 Can't open C skeleton file.

        998 Source  file  name  with  invalid  extension (use .i or
            .[2-7]i).

        997 Illegal possession of a controlled unary operator.









































       






                                  - 51 -



       _1_0_.  _T_h_e _C_-_I_N_T_E_R_C_A_L _C_o_m_p_i_l_e_r

            "And yet it was a very clever pudding to invent."

            "What did you mean it to  be  made  of?"  Alice  asked,
            hoping  to  cheer  him  up,  for the poor Knight seemed
            quite low-spirited about it.

            "It began with  blotting-paper,"  the  Knight  answered
            with a groan.

            "That wouldn't be very nice, I'm afraid --"

            "Not  very  nice _a_l_o_n_e," he interrupted, quite eagerly,
            "but you've no idea what a difference it makes,  mixing
            it  with other things -- such as gunpowder and sealing-
            wax."

       This section  describes  the  use  of  ick,  the  C-INTERCAL
       compiler.  Information  specific to the other known INTERCAL
       compilers appears in the following sections. These  sections
       are  less  useful,  since  the other compilers are no longer
       available, but they are  retained  to  provide  a  sense  of
       history,  and  because any information regarding INTERCAL is
       really too scarce to discard.

       _1_0_._1  _C_h_a_r_a_c_t_e_r _S_e_t

       The C-INTERCAL compiler uses ASCII rather  than  EBCDIC.  We
       follow  the  Atari  implementation  (see  section  )  by (a)
       replacing the change sign (c/) with  big  money  ($)  as  the
       mingle  operator,  and (b) replacing the bookworm (V-) symbol
       with what (?) as the XOR operator.

       Version 0.18 and later  versions  accept  the  Latin-1  (ISO
       8859-1)  character  set, which is a superset of ASCII.  As a
       result, 0xA2  (c/),  0xA3  (quid),  and  0xA4  (zlotnik)  are
       accepted as mingle operators.

       Version  0.20  and  later  versions  also accept UTF-8 as an
       alternative to Latin-1.  The above three currency  operators
       will  be  accepted in either Latin-1 or UTF-8 format.  UTF-8
       format is required if you wish to use any  of  EURO-CURRENCY
       SIGN,  COLON  SIGN  (that's  Costa  Rican  dinero,  not  the
       Intercal two-spot), CRUZEIRO SIGN, FRENCH FRANC  SIGN,  LIRA
       SIGN,  MILL  SIGN,  NAIRA SIGN, PESETA SIGN, RUPEE SIGN, WON
       SIGN, NEW SHEQEL SIGN, DONG SIGN, EURO SIGN,  BENGALI  RUPEE
       MARK,  BENGALI  RUPEE  SIGN,  or  THAI CURRENCY SYMBOL BAHT.
       (Isn't internationalization  wonderful?)   Furthermore,  you
       can use the Intercal character FOR ALL to represent the what
       operator.

       _1_0_._2  _U_s_a_g_e _a_n_d _C_o_m_p_i_l_a_t_i_o_n _O_p_t_i_o_n_s


       






                                  - 52 -



       To  compile  an INTERCAL program `foo.i' to executable code,
       just do

               ick foo.i

       There's a -c option that leaves  the  generated  C  code  in
       place  for  inspection  (suppressing  compilation to machine
       code), a -d option that enables verbose parse reporting from
       the yacc/bison parser, a  -t  option  that  requires  strict
       INTERCAL-72   compliance   (rejecting   COME  FROM  and  the
       extensions for bases other  than  two),  a  -b  option  that
       disables the INTERCAL-72 random-bug feature (error 774), and
       an -O option that enables the (hah!) optimizer. Invoking ick
       -? prints a usage message.

       Another  compilation  switch  affects  C-INTERCAL's  runtime
       behavior. The `-C' option forces output in "clockface" mode,
       for superstitious users who believe writing "IV" upside-down
       offends IVPITER and would rather see IIII.

       _1_0_._3  _R_u_n_t_i_m_e _O_p_t_i_o_n_s

       Every C-INTERCAL runtime also  accepts  certain  options  at
       runtime.   These  include  [+/-]help,  [+/-]traditional, and
       [+/-]wimpmode.   The  help  option  (with  either  +  or  -)
       triggers  a  'usage'  message.  The  +traditional  option is
       presently a no-op.

       Steve  explains:  "The   wimpmode   option   is   the   most
       interesting.  I found myself always running my test programs
       with filters  on  both  ends  to  work  around  the  'nifty'
       INTERCAL  number representations. This was so painful that I
       decided it would be _l_e_s_s painful (and a lot less code) if  I
       added  a  'wimp' option. With the +wimpmode option, the user
       is subjected to a humiliating message about what a  wimp  he
       or she is to use this mode, but after that is allowed to use
       conventional numerical notation. While such a mode doubtless
       violates  to  some  extent the INTERCAL philosophy, the fact
       that  an  'unbutcher'  command  has  been   posted   clearly
       indicates  the need for it. Anyway ... if you don't like it,
       don't use it ... the default is  -wimpmode  (i.e.  _n_o_t  wimp
       mode)."

       _1_0_._4  _P_L_E_A_S_E _P_o_l_i_t_e_s_s_e _C_h_e_c_k_i_n_g

       A  feature  of  INTERCAL-72  not  documented in the original
       manual was that it required a  certain  level  of  politesse
       from  the  programmer.  If  fewer  than 1/5th of the program
       statements included the PLEASE qualifier, the program  would
       be  rejected as insufficiently polite. If more than 1/3rd of
       them included PLEASE,  the  program  would  be  rejected  as
       excessively polite.

       This  check  has  been  implemented in C-INTERCAL. To assist

       






                                  - 53 -



       programmers in coping with it, the intercal.el mode included
       with the distribution randomly  expands  "do  "  in  entered
       source to "PLEASE DO" 1/4th of the time.

       _1_0_._5  _L_o_c_a_l_i_z_a_t_i_o_n_: _A_n_c_i_e_n_t _R_o_m_a_n

       Version  0.18  and  later  versions  of C-Intercal have been
       localized for Ancient  Roman  as  well  as  English-speaking
       locales.    This  means  that  Latin-language  keywords  are
       accepted  as  equivalents   for   the   English-based   ones
       traditionally  used.   See src/lexer.l for details, as we do
       not propose to break Priscian's head  (publicly  expose  our
       ignorance of Latin) here.










































       






                                  - 54 -



       _1_1_.  _T_h_e _A_t_a_r_i _I_m_p_l_e_m_e_n_t_a_t_i_o_n

            "Perhaps it doesn't understand English," thought Alice.
            "I  daresay it's a French mouse, come over with William
            the  Conqueror."  (For,  with  all  her  knowledge   of
            history,  Alice  had  no very clear notion how long ago
            anything had happened.)

       The  Atari  800  implementation,  actually  a  generic  6502
       implementation  that  was  begun in 1982 by Mike Albaugh and
       Karlina Ott, was never completed sufficiently to target  the
       Atari  cartridge  format.   These  notes  were added by Mike
       Albaugh when he typed in the  original  INTERCAL-72  manual,
       which up to that point had existed only in paper copies.

       The  Atari  implementation  of  INTERCAL  differs  from  the
       original Princeton version primarily in  the  use  of  ASCII
       rather  than  EBCDIC. Since there is no "change" sign (c/) in
       ASCII, we have substituted the "big money" ($) as the mingle
       operator.  We  feel  that  this  correctly  represents   the
       increasing   cost  of  software  in  relation  to  hardware.
       (Consider that in 1970 one could get RUNOFF for free, to run
       on a $20K machine, whereas today a  not  quite  as  powerful
       formatter costs $99 and runs on a $75 machine.) We also feel
       that  there should be no defensible contention that INTERCAL
       has any sense.  Also, since  overpunches  are  difficult  to
       read  on  the  average VDT, the exclusive-or operator may be
       written ?. This correctly  expresses  the  average  person's
       reaction on first encountering exclusive-or, especially on a
       PDP-11.  Note  that in both of these cases, the over-punched
       symbol may also be used if one is masochistic, or  concerned
       with  portability  to  the  Princeton  compiler. The correct
       over-punch for "change" is "c<backspace>/" and  the  correct
       over-punch  for  V-  is  "V<backspace>-". These codes will be
       properly printed if you  have  a  proper  printer,  and  the
       corresponding  EBCDIC  code  will  be  produced  by the /IBM
       option on the LIST command.


















       






                                  - 55 -



       _1_2_.  _T_h_e _P_r_i_n_c_e_t_o_n _C_o_m_p_i_l_e_r

            "My name is Alice, so please your Majesty," said  Alice
            very politely; but she added, to herself, "Why, they're
            only a pack of cards, after all. I needn't be afraid of
            them!"

       The  Princeton  compiler,  written  in SPITBOL (a variant of
       SNOBOL), performs the compilation in two stages.  First  the
       INTERCAL  source  is converted into SPITBOL source, then the
       latter is compiled and executed.

       It should be noted that  the  Princeton  compiler  fails  to
       properly interpret certain multiply-subscripted expressions,
       such as:

               ",1SUB",2SUB#1"#2"

       This  is  not  a  "bug".  Being  documented,  it is merely a
       "restriction". Such cases may  be  resolved  by  alternating
       sparks and ears in various levels of expression nesting:

               ",1SUB',2SUB#1'#2"

       which  is  advisable in any case, since INTERCAL expressions
       are unreadable enough as is.

       Since  there  is  currently  no  catalogued  procedure   for
       invoking  the  compiler,  the  user must include the in-line
       procedure  shown  in  Figure  3  in  his  job   before   the
       compilation  step.  Copies  of this in-line procedure may be
       obtained at any keypunch if the proper keys are struck.

       The compiler is then executed in the usual manner:


               // EXEC INTERCAL[,PARM='parameters']
               //COMPILE.SYSIN DD *
               {INTERCAL source deck}
               /*
               //EXECUTE.SYSWRITE DD *
               {input data}
               /*


       The various parameters are described following  the  in-line
       procedure.  At most one parameter from each set may apply to
       a given compilation; if more than  one  are  specified,  the
       results  are  undefined,  and  may  vary  depending upon the
       particular  set  of  options.  The  default  parameters  are
       underlined.




       






                                  - 56 -



               //INTERCAL PROC
               //COMPILE EXEC PGM=INTERCAL
               //STEPLIB DD DSN=U.INTERCAL.LIBRARY,DISP=SHR
               //             DD DSN=SYS1.FORTLIB,DISP=SHR
               //SYSPRINT DD SYSOUT=A,DCB=(BLKSIZE=992,LRECL=137,RECFM=VBA)
               //SYSPUNCH DD DUMMY
               //SCRATCH DD DSN=&COMPSET,UNIT=SYSDA,SPACE=(CYL,(3,1)),DISP=(,PASS)
               //EXECUTE EXEC PGM=EXECUTE,COND=(4,LT)
               //SOURCES DD DSN=U.INTERCAL.SOURCES,DISP=SHR   [4]
               //STEPLIB DD DSN=U.INTERCAL.LIBRARY,DISP=SHR
               //             DD DSN=SYS5.SPITLIB,DISP=SHR
               //             DD DSN=SYS1.FORTLIB,DISP=SHR
               //SYSIN DD DSN=&COMPSET,DISP=(OLD,DELETE)
               //SYSOBJ DD SYSOUT=B,DCB=(BLKSIZE=80,LRECL=80,RECFM=F)
               //SYSPRINT DD SYSOUT=A,DCB=(BLKSIZE=992,LRECL=137,RECFM=VBA)
               //SYSPUNCH DD DUMMY
               // PEND

             Figure 3.  Inline procedure for using INTERCAL.

       _O_P_T
       NOOPT
            In the default mode, the compiler will print a list  of
            all  options  in  effect,  including  the  defaults for
            unspecified parameter groups and the  effective  option
            for  those  sets  where  one was specified. If NOOPT is
            requested, it causes the default mode to be assumed.

       _O_P_T_S_U_B
       NOOPTSUB
       NOSUB
            Unless 'NOOPTSUB' is requested, the System  Library  is
            optimized,  resulting  in much more rapid processing of
            function calls. Specifying  NOOPTSUB  causes  the  non-
            optimized INTERCAL code shown in section
             to  be  used,  whereas  NOSUB requests that the System
            Library be omitted altogether.

       IAMBIC
       _P_R_O_S_E
            The IAMBIC parameter  permits  the  programmer  to  use
            poetic  license  and thus write in verse. If the reader
            does  not  believe  it  possible  to  write  verse   in

       ____________________

       4. Pending  acquisition  of SPITBOL release 3.0, the SOURCES
          DD card must be replaced by the five cards:

                  //NOOPTPFX DD DSN=U.INTERCAL.SOURCES(NOOPTPFX),DISP=SHR
                  //NOOPTSUB DD DSN=U.INTERCAL.SOURCES(NOOPTSUB),DISP=SHR
                  //OPTPFX DD DSN=U.INTERCAL.SOURCES(OPTPFX),DISP=SHR
                  //OPTSUB DD DSN=U.INTERCAL.SOURCES(OPTSUB),DISP=SHR
                  //PRELIM DD DSN=U.INTERCAL.SOURCES(PRELIM),DISP=SHR








                                  - 57 -



            INTERCAL,  he  should send the authors a stamped, self-
            addressed envelope, along with  any  INTERCAL  program,
            and they will provide one which is verse.

       _F_O_R_M_A_T
       NOFORMAT
            In  FORMAT  mode,  each  statement  printed is put on a
            separate line (or lines). In NOFORMAT mode,  the  free-
            format  source  is  printed  exactly as input.  In this
            latter case, statement numbers are  provided  only  for
            the  first  statement  on  a card, and they may be only
            approximate. Also, unrecognizable  statements  are  not
            flagged.

       SEQ
       _N_O_S_E_Q
            If  the  source deck has sequence numbers in columns 73
            through 80, specifying 'SEQ'  will  cause  them  to  be
            ignored.

       SOURCE
       _N_O_S_O_U_R_C_E
            If   NOSOURCE   is  selected,  all  source  listing  is
            suppressed.

       LIST
       _N_O_L_I_S_T
            If LIST is specified, the compiler will provide a  list
            of  statement  numbers  catalogued according to type of
            statement. The compiler  uses  this  table  to  perform
            abstentions by gerund.

       WIDTH=nn
            This  sets  the  width (in number of characters) of the
            output line for FORMAT mode output. The default is 113322..

       CODE
       _N_O_C_O_D_E
            Include 'CODE'  in  the  parameter  list  to  obtain  a
            listing  of the SPITBOL code produced for each INTERCAL
            statement.

       LINES=nn
            This determines the number of lines  per  page,  during
            both compilation and execution. The default is 6600..

       DECK
       _N_O_D_E_C_K
            Selecting 'DECK' will cause the compiler to punch out a
            SPITBOL  object  deck  which  may  then  be run without
            reinvoking the INTERCAL (or SPITBOL) compiler.

       _K_I_D_D_I_N_G


       






                                  - 58 -



       NOKIDDING
            Select NOKIDDING to eliminate the snide  remarks  which
            ordinarily accompany INTERCAL error messages.

       _G_O
       NOGO
            Specifying   'NOGO'  will  cause   the  program  to  be
            compiled but not  executed.  EXECUTE/NOEXECUTE  may  be
            substituted  for  GO/NOGO,  but  this will result in an
            error, and GO will be assumed.

       _B_U_G
       NOBUG
            Under the default, there is a fixed  probability  of  a
            fatal  compiler  bug  being  worked  at random into the
            program being compiled. Encountering  this  bug  during
            execution  results in error message 774 (see section ).
            This probability is reduced to zero under 'NOBUG'. This
            does not affect the probability (presumably negligible)
            of error message 778.

       _1_2_._1  _O_t_h_e_r _I_N_T_E_R_C_A_L _C_o_m_p_i_l_e_r_s

       There are no other INTERCAL compilers. [5]

























       ____________________

       5. This assertion in the INTERCAL-72  manual  was  blatantly
          contradicted  by  some  notes  on an Atari implementation
          included at the  end  of  the  manual.   So,  you  expect
          compiler manuals to be consistent?







                                  - 59 -



                               TTOONNSSIILL AA[[66]]




            "Of  course  they  answer  to  their  names?"  the Gnat
            remarked carelessly.

            "I never knew them to do it."

            "What's the use of their having names," the Gnat  said,
            "if they wo'n't answer to them?"
            "No  use  to _t_h_e_m," said Alice; "but it's useful to the
            people that name them, I suppose. If not, why do things
            have names at all?"

            "I ca'n't say," the Gnat replied. "Further on,  in  the
            wood down there, they've got no names -- however, go on
            with your list...."

       The Official INTERCAL Character Set

       Tabulated next are all  the  characters  used  in  INTERCAL,
       excepting  letters  and  digits,  along with their names and
       interpretations. Also included are  several  characters  not
       used  in  INTERCAL, which are presented for completeness and
       to allow for future expansion.





















       ____________________

       6. Since all other reference manuals have Appendices, it was
          decided  that  the  INTERCAL  manual  should contain some
          other type of removable organ.

       7. This footnote intentionally unreferenced.







                                  - 60 -



       +------------------------------------------------------------------------------+
       | Character   Name                             Use (if any)                    |
       +------------------------------------------------------------------------------+
       | .           spot                             identify 16-bit variable        |
       | :           two-spot                         identify 32-bit variable        |
       | ,           tail                             identify 16-bit array           |
       | ;           hybrid                           identify 32-bit array           |
       | #           mesh                             identify constant               |
       | =           half-mesh                                                        |
       | '           spark                            grouper                         |
       | `           backspark                                                        |
       | !           wow                              equivalent to spark-spot        |
       | ?           what                             unary logical XOR               |
       | "           rabbit-ears                      grouper                         |
       | ".           rabbit                           equivalent to ears-spot         |
       | |           spike                                                            |
       | %           double-oh-seven                  percentage qualifier            |
       | -           worm                             used with angles                |
       | <           angle                            used with worms                 |
       | >           right angle                                                      |
       | (           wax                              precedes line label             |
       | )           wane                             follows line label              |
       | [           U turn                                                           |
       | ]           U turn back                                                      |
       | {           embrace                                                          |
       | }           bracelet                                                         |
       | *           splat                            flags invalid statements        |
       | &           ampersand [9]                    unary logical AND               |
       | V           V (or book)                      unary logical OR                |
       | V-           bookworm (universal qualifier)   unary logical XOR (INTERCAL-72) |
       | $           big money                        binary mingle                   |
       | c/           change                           binary mingle (INTERCAL-72)     |
       | ~           sqiggle                          binary select                   |
       | _           flat worm                                                        |
       | -           overline                         indicates "times 1000"          |
       | +           intersection                     separates list items            |
       | /           slat                                                             |
       | \           backslat                                                         |
       | @           whirlpool                        unary logical BUT (TriINTERCAL) |
       |             hookworm                                                         |
       | ^           shark (or simply sharkfin)       unary logical XOR (TriINTERCAL) |
       | #*[]          blotch                                                           |
       |             bunghole                                                         |
       | (R)         name grabber                                                     |
       | x           andrew cross                                                     |
       |             norwegian minus                                                  |
       | (C)         text grabber                                                     |
       |             swash                                                            |
       |             microscope                                                       |
       | +-          interworm                                                        |
       | -'           half turn                                                        |
       |             quid                             binary mingle                   |
       |             zlotnik                          binary mingle                   |
       +------------------------------------------------------------------------------+

       






                                  - 61 -



               Table 2 (top view). INTERCAL character set.



















































       ____________________

       9. Got any better ideas?




