This python library was mostly implemented for a talk I gave at PythonNW in Manchester
It has an example of a PEG for parsing dice expressions and maths, implemented using parsimonious.
A dice expression looks like 2d6+3 or (1d6+2)*3 + 3d4. You can even input slightly foolish dice expressions like 1d8*1d8
Install dependencies with pipenv install.
The module can be executed via python -m. If called with no arguments, it starts up an interactive shell.
python -m parsimonious_dice
> 2d6+3
9
It's not currently on pypi, but with flit install you can install it locally.