ToyPy

A toy Python 3 interpreter written in pure Python, just for fun.

Features

• Uses the lark grammar parser - https://github.com/lark-parser/lark
• Supports variable assignment with arithmetic expressions

Working example

Test file - test.py:

# The parser handles order of operations, making our interpreter more simple
x = 3 + 16 * 2
y = 5 - 16 / 2
z = 5 - 16 / 2 * 52 + 9 * 2 / 18 + 82 - (52 / 2) / 82 - 2

# Test reassignment
b = 5 + 1
b = 6 + 2

Execution:

# The interpreter reads a file called test.py
> python interpreter.py
Parsing time (seconds): 0.0014879070000000105
Execution time (seconds): 3.261599999992981e-05
========= Stack Locals ==========
{'x': 35, 'y': -3.0, 'z': -330.3170731707317, 'b': 8}

Future Work

• Redesign all data objects to use objects https://docs.python.org/3.7/reference/datamodel.html
• See data type implementations in Python to Go transcompiler for inspiration on core type implementations https://github.com/google/grumpy/tree/master/runtime
• Implement more features such as function calls with their own stack frames
• Refactor the run_instruction main loop to support many data handlers
• Implement a print() function
• Allow any file name to be run in the interpreter
• Have more fun