# Glossary

application level
  applevel code is normal Python code running on top of the PyPy or CPython interpreter (see interpreter level)
CPython
  The "default" implementation of Python, written in C and distributed by the PSF on http://www.python.org.
interpreter level
  Code running at this level is part of the implementation of the PyPy interpreter and cannot interact normally with application level code; it typically provides implementation for an object space and its builtins.
mixed module
  a module that accesses PyPy's interpreter level. The name comes from the fact that the module's implementation can be a mixture of application level and interpreter level code.
object space
  The Object Space (often abbreviated to "objspace") creates all objects and knows how to perform operations on the objects. You may think of an object space as being a library offering a fixed API, a set of operations, with implementations that a) correspond to the known semantics of Python objects, b) extend or twist these semantics, or c) serve whole-program analysis purposes.
stackless
  Technology that enables various forms of non conventional control flow, such as coroutines, greenlets and tasklets. Inspired by Christian Tismer's Stackless Python.
standard interpreter

  It is the subsystem implementing the Python language, composed of the bytecode interpreter and of the standard objectspace.

  ebuilt constant
    In RPython module globals are considered constants. Moreover, global (i.e. prebuilt) lists and dictionaries are supposed to be immutable ("prebuilt constant" is sometimes abbreviated to "pbc").