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gpython is a part re-implementation / part port of the Python 3.4 interpreter to the Go language, "batteries not included".

It includes:

  • runtime - using compatible byte code to python3.4
  • lexer
  • parser
  • compiler
  • interactive mode (REPL) (try online!)

It does not include very many python modules as many of the core modules are written in C not python. The converted modules are:

  • builtins
  • marshal
  • math
  • time
  • sys


Gpython is a Go program and comes as a single binary file.

Download the relevant binary from here:

Or alternatively if you have Go installed use

go get

and this will build the binary in $GOPATH/bin. You can then modify the source and submit patches.


Gpython was written as a learning experiment to investigate how hard porting Python to Go might be. It turns out that all those C modules are a significant barrier to making a fully functional port.


The project works well enough to parse all the code in the python 3.4 distribution and to compile and run python 3 programs which don't depend on a module gpython doesn't support.

See the examples directory for some python programs which run with gpython.

Speed hasn't been a goal of the conversions however it runs pystone at about 20% of the speed of cpython. The pi test runs quicker under gpython as I think the Go long integer primitives are faster than the Python ones.

There are many directions this project could go in. I think the most profitable would be to re-use the grumpy runtime (which would mean changing the object model). This would give access to the C modules that need to be ported and would give grumpy access to a compiler and interpreter (gpython does support eval for instance).

I (@ncw) haven't had much time to work on gpython (I started it in 2013 and have worked on it very sporadically) so someone who wants to take it in the next direction would be much appreciated.

Limitations and Bugs


Similar projects

  • grumpy - a python to go transpiler


You can chat with the go-python community (or which gpython is part) at or on the Gophers Slack in the #go-python channel.


This is licensed under the MIT licence, however it contains code which was ported fairly directly directly from the cpython source code under the PSF LICENSE.