Getting Started


This guide is specific to the pre-release experimental state of this library. As the Python library becomes publicly available and the required server modifications are merged into the mainline of Cryptol, installation will be much more straightforward.

Please report any difficulties you find with this library at the issue tracker.

To use pycryptol, both the pycryptol Python library and the cryptol-server Haskell executable must be installed. This guide assumes that you already have Python and pip installed, and that you have a Haskell toolchain with GHC 7.8.4 or newer capable of building Cryptol.

Installing ZeroMQ Development Libraries

The Python library and the Cryptol server both require the development libraries for ZeroMQ version 4 or higher. Your OS or package manager (such as Homebrew or apt-get) should have a ZeroMQ package, but if the version is too old, see the ZeroMQ site for more on how to download and install the correct library.

Installing the Python Library

The Python library is most easily installed using pip:

pip install git+ \
    --allow-external BitVector


The BitVector library used in pycryptol is hosted outside the usual PyPI repository, and so requires the --allow-external flag when installing.

Installing the Cryptol Server

This guide assumes that you are already have GHC 7.8.4 or newer, and are able to build Cryptol from a GitHub checkout; see the Cryptol documentation for instructions.

  1. Clone the Cryptol repository:

    $ git clone
    $ cd cryptol
  2. Build the Cryptol distribution with the CRYPTOL_SERVER option set:

    $ CRYPTOL_SERVER=1 make dist
  3. Extract the resulting .tar or .zip file to a location of your choice as you would with a normal Cryptol release.

  4. Make sure your system PATH contains the location you extracted the distribution. You should be able to start the cryptol-server executable at your shell (you can shut the server down after testing by pressing Ctrl-C):

    $ cryptol-server
    [cryptol-server] coming online at tcp://

Testing your Installation

With the pycryptol library and the cryptol-server executable installed, you can use the Python interpreter to test whether all of the components were successfully installed. For example:

$ python
Python 2.7.9 (default, Feb 10 2015, 03:28:08)
[GCC 4.2.1 Compatible Apple LLVM 6.0 (clang-600.0.56)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> import cryptol
>>> cry = cryptol.Cryptol()
>>> prelude = cry.prelude()
>>> int(prelude.eval("1+1"))