SpyType - Simple Python Function Type Specification Generator

SpyType is a research project that aims to create specifications for Python functions. Inference is done using the following:

• a set of stubs snapshotted from the Typeshed project (https://github.com/python/typeshed) - found in the path sheds/builtins.pyi of the current project
• the Python Language Bindings for Maude (https://github.com/fadoss/maude-bindings)
• slightly modified versions of model.py, builder.py and __init__.py from the Staticfg project (https://github.com/coetaur0/staticfg/tree/master) - to build the control flow graph and add extra metadata to it

This project is a work in progress and the name SpyType has been chosen as a tribute to a very good and well-established type inference solution, namely Pytype (https://google.github.io/pytype/)

Worthy mentions:

• Mopsa Static Analyzer (shout-out to Raphael Monat for mopsa-python-types): https://gitlab.com/mopsa/mopsa-analyzer
• Typpete: https://github.com/caterinaurban/typpete

Quickstart

SpyType has been tested on Python 3.11 and Python 3.12. The recommended way to use this is to create a virtual environment and install the required libraries using the requirements.txt file. To use the tool, use the following command line:

usage: python spytype.py [-h] -i INPUT [-f [FUNCTIONS ...]] -o OUTPUT [-v] [-r]

A POC for Python function type inference using Maude solver.

options:
  -h, --help            show this help message and exit
  -i INPUT, --input INPUT
                        Input file containing Python functions
  -f [FUNCTIONS ...], --functions [FUNCTIONS ...]
                        Optional list of functions to be inferred. If this is omitted, then all functions from the input file are inferred
  -o OUTPUT, --output OUTPUT
                        Path to the output file for writing results
  -v, --verbose         Show information in every CFG node (inferfunc_* images)
  -r, --restrictive     (EXPERIMENTAL) Apply a restrictive approach for function specification parameter types.

Note

The set of specifications used as a basis for inference is the united_specs.py file found in the root of the project. To re-generate this file based on the information in the stubs found sheds folder, simply run:

python pyiparser_2.py

This creates the united_specs.py file by translating the stubs into SpyType's internal specification format. Also, some specifications are added that are used for parsing AST nodes from functions.

Simple Usage Examples:

Example 1

python spytype.py -i benchmarks\mine\benchfuncs.py -f while_1 -o while_1.spytype

This will write the inferred specifications for the function named while_1 from the benchfuncs.py file into while_1.spytype. The output has the following form:

---------------------------------
while_1 specs
---------------------------------
while_1 : {
	((x:int) -> (return:list < int >)),
}

Example 2

python spytype.py -i benchmarks\mine\benchfuncs.py -o benchfuncs.spytype

This will write the inferred specifications for every function in the benchfuncs.py file into benchfuncs.spytype.