neat-interpolation-0.5.1.4: Quasiquoter for neat and simple multiline text interpolation

Safe Haskell | None
Language | Haskell2010

NeatInterpolation

Description

NeatInterpolation provides a quasiquoter for producing strings with a simple interpolation of input values. It removes the excessive indentation from the input and accurately manages the indentation of all lines of interpolated variables. But enough words, the code shows it better.

Consider the following declaration:

    {-# LANGUAGE QuasiQuotes #-}

    import NeatInterpolation
    import Data.Text (Text)

    f :: Text -> Text -> Text
    f a b =
      [trimming|
        function(){
          function(){
            $a
          }
          return $b
        }
      |]

Executing the following:

    main = Text.putStrLn $ f "1" "2"

will produce this (notice the reduced indentation compared to how it was declared):

    function(){
      function(){
        1
      }
      return 2
    }

Now let's test it with multiline string parameters:

    main = Text.putStrLn $ f
      "{\n  indented line\n  indented line\n}"
      "{\n  indented line\n  indented line\n}"

We get

    function(){
      function(){
        {
          indented line
          indented line
        }
      }
      return {
        indented line
        indented line
      }
    }

See how it neatly preserved the indentation levels of lines the variable placeholders were at?

If you need to separate variable placeholder from the following text to prevent treating the rest of line as variable name, use escaped variable:

    f name = [trimming|this_could_be_${name}_long_identifier|]

So

    f "one" == "this_could_be_one_long_identifier"

If you want to write something that looks like a variable but should be inserted as-is, escape it with another `$`:

    f word = [trimming|$$my ${word} $${string}|]

results in

    f "funny" == "$my funny ${string}"

Synopsis

- trimming :: QuasiQuoter
- untrimming :: QuasiQuoter
- text :: QuasiQuoter

# Documentation

trimming :: QuasiQuoter Source #

Trimmed quasiquoter variation. Same as `untrimming`, but also removes the leading and trailing whitespace.

untrimming :: QuasiQuoter Source #

Untrimmed quasiquoter variation. Unindents the quoted template and converts tabs to spaces.

text :: QuasiQuoter Source #

An alias to `trimming` for backward-compatibility.