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Blip, a bytecode compiler and interpreter for Python 3

Blip compiles Python 3 source files to bytecode. The output bytecode is compatible with the CPython interpreter - the reference, and most commonly used, Python implementation.

For example, given a Python 3 source file called, the command:

   blip -c

produces a bytecode file called foo.pyc. The bytecode can be executed by passing it as an argument to a CPython interpreter:

   python3 foo.pyc

or you can pass it as an argument to blip:

   blip foo.pyc

If you omit the -c argument then blip will compile the Python code to bytecode and then immediately execute it:


If you don't provide a Python file as input to blip it will start a REPL where you can type in Python statements and have them immediately executed:


The blip source tree also includes code for a program called readpyc, which can be used for pretty printing the contents of .pyc files:

   readpyc foo.pyc


usage: blip [options] [<input file>]
  [--version]               Show the version number of blip.
  [-h,--help]               Display a help message.
  [--magic <magic number>]  Magic number to include in pyc file header.
  [--dumpScope]             Dump the variable scope.
  [--dumpAST]               Dump the abstract syntax tree.
  [-c,--compile]            Compile .py to .pyc but do not run the program.
  [<input file>]            Name of the input Python file, either .py or .pyc

Each version of CPython uses a magic number in the .pyc file header. This is to prevent the wrong version of CPython from being used to interpret a given .pyc file. The current version of blip generates bytecode which is compatible with Python 3.3, and automatically uses the correct magic number for that version. If you want to use a different magic number you can specify it on the command line with the --magic argument. You might need to consult the source code of CPython to find out what magic number to use for a given CPython version.

License and Copyright

Blip is distributed as open source software under the terms of the BSD License (see the file LICENSE in the top directory).

Author: Bernie Pope, copyright 2012 onwards.

Building and installing

Blip uses the cabal infrastructure for configuring, building and installation. However, for convenience a Makefile is provided to orchestrate the process.

To build (in the top directory of the source tree):

cabal build all

To install blip:

cabal install --overwrite-policy=always blip

To install readpyc:

cabal install --overwrite-policy=always readpyc 


Blip uses shelltestrunner for regression testing. Tests can be run like so:

PATH=$HOME/.cabal/bin/:$PATH ~/.cabal/bin/shelltest --color --execdir test/regression -- -j1

Change -j1 to a higher number if you want to speed up testing and use more CPU cores. For example, use -j4 to use 4 CPU cores.

Shelltestrunner can be installed from Hackage:

cabal install shelltestrunner

Blip is a work-in-progress, so some tests might fail.


A bytecode compiler for Python 3







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