python-pickle is a Haskell library to serialize and deserialize Python objects using the Python Pickle format. It supports protocols 0-5 for deserializing and uses protocol 2 for serialization.
It offers a Value data type to represent Python objects, and two functions,
pickle and unpickle, to serialize and deserialize such values.
In practice the Python Pickle format is a list of serialized opcodes. By deserializing those opcodes then interpreting them, one can reconstruct the original object. Interpreting the opcodes is done using a simple stack-based Pickle machine.
If you want to learn about the Pickle format, the standard Python pickletools
library source is a good place to start.
Installing from Hackage with Cabal is straightforward:
> cabal update ; cabal install python-pickle
The development version can be installed by cloning the Git repository and using Cabal:
> git clone git://github.com/noteed/python-pickle.git
> cd python-pickle && cabal install
A pickle executable is provided. It can be used to inspect a pickle file
(i.e. a file containing a pickled Python object).
- Not all opcodes are implemented.
- Strings are not correctly escaped.
- Can pickle (i.e. serialize) only with protocol 2.
- Unpickling a protocol 0 string (which uses literal representation of e.g. float values) is not accurate (possibly the Python implementation is not accurate either).