Mini Scheme Interpreter

Overview

This project implements an interpreter for a simplified version of the Scheme language, derived from Lisp. It supports key features such as basic arithmetic operations, function definitions, list management, and control structures. The interpreter is built using Python and ANTLR, providing a robust foundation for functional programming exploration.

Key Features

• Basic Operations: Arithmetic, logical, and relational operations.
• Function and Constant Definitions: Support for global function definitions and immutable constants.
• List Management: Operations like car, cdr, cons, and null?.
• Control Structures: Simple and multiple conditionals with if and cond.
• Input and Output: Functions like read, display, and newline.
• Local Variables: Support for local declarations using let.
• Recursion: Implementation of recursive functions.

Implementation Details

The interpreter leverages Python and ANTLR for parsing and executing Scheme expressions. Key components include:

• Function: Represents user-defined functions with parameters and body.
• Environment: Manages scopes for variables and functions.
• EvalVisitor: Core evaluator for traversing the syntax tree and executing expressions.

The system supports nested expressions, recursive calls, and robust error handling, ensuring accurate execution of Scheme programs.

Grammar

grammar scheme;

root : expr* EOF;

expr
    : ( ''(' | '(' ) expr* ')' #expression
    | BOOLEAN #bool
    | NUMBER #num
    | IDENTIFIER #id
    | OPERATOR #op
    | STRING #str
    ;

OPERATOR: '+'|'-'|'*'|'/'|'<'|'>'|'='|'<='|'>='|'and'|'or'|'not'|'mod';
IDENTIFIER: [a-zA-Z][a-zA-Z0-9\-]* '?'?;
NUMBER : '-'? [0-9]+ ;
BOOLEAN : '#t' | '#f';
STRING : '"' .*? '"';
WS  : [ \t\n]+ -> skip;
COMMENT: ';' .*? '\n' -> skip;

      

Explore More

• GitHub Repository