tanhuang01/eva_type_checker

Abstract

This document outlines a concise type-checker for Eva, supporting a range of type-checking capabilities:

• Mathematical Binary Operations: Handles addition, subtraction, multiplication, and division, including logical combinations thereof.
• Comparison Operators: Supports greater than (>), less than (<), greater than or equal to (>=), less than or equal to (<=), and equals (==).
• Variable Definition and Update: Manages variable declarations and updates within the scope.
• Branching: Incorporates if conditions for flow control.
• Lambda Functions: Allows anonymous function definitions.
• Function Declarations and Calls: Supports defining and invoking functions.
• Generic Function: Facilitates generic programming by allowing functions to operate on various types.

IDE Setup

• PyCharm: Version 2022.3.2
• Python: Version 3.11
• Relevant Third-party Libraries:
  • sexpdata
  • pyInstaller

Project Structure

• parser/: Converts raw Eva language into list form, e.g., (+ 1 3) -> ['+', 1, 3].
• tests/: Contains test cases.
• type_env.py: Defines the type-checking environment, preserving variables within the current and parent blocks.
• EvaTC.py: Houses the main logic of the type checker.
• Type.py: Defines the types utilized in Eva.
• main.py: Acts as the entry point of the interpreter.

Running the Project

To generate an executable for the project, execute the following command in the terminal from the directory containing main.py:

pyinstaller --onefile --name eva-tc main.py

This command creates an executable named eva-tc in the dist/ directory. Usage examples include:

eva-tc -e "(+ 1 4)"
# Output: No Error!

eva-tc -e "(+ 1 '4')"
# Output: RuntimeError: Expected Type.number for "3" in expression, but got Type.string.

Code Examples

Additional code examples are available in the tests/ directory.