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LISP Integration

Overview

Grapa's LISP integration demonstrates how the language can implement its own inspiration. Since Grapa is LISP-inspired with late-binding, functional programming, and code-as-data capabilities, implementing LISP syntax provides a natural bridge between traditional LISP concepts and Grapa's modern features.

This integration showcases: - LISP syntax parsing using Grapa's executable BNF - Functional programming with LISP-style expressions - Macro system implementation - List processing with native Grapa operations - Dynamic function definition and evaluation

Key LISP Concepts in Grapa

1. S-Expressions

LISP's fundamental data structure - nested lists representing code and data:

/* LISP S-expression syntax */
custom_command = rule '(' $STR* ')' { op(expression:$2){
    /* Parse and evaluate S-expression */
    return evaluate_sexp($2);
} };

/* Usage */
op()("(+ 1 2 3)")();  /* Returns 6 */
op()("(list 1 2 3)")();  /* Returns [1, 2, 3] */

2. Function Definition

Define new LISP functions using defun:

/* LISP function definition */
custom_command = rule '(defun' $STR '(' $STR* ')' $STR* ')' { 
    op(name:$2, params:$4, body:$6){
        /* Store function definition */
        $global.lisp_functions[$2] = {
            params: $4,
            body: $6
        };
        return "Function " + $2 + " defined";
    }
};

/* Usage */
op()("(defun factorial (n) (if (= n 0) 1 (* n (factorial (- n 1)))))")();
op()("(factorial 5)")();  /* Returns 120 */

3. Conditional Expressions

LISP-style conditionals with if and cond:

/* LISP if statement */
custom_command = rule '(if' $STR $STR $STR ')' { 
    op(condition:$2, then:$3, else:$4){
        if (evaluate_sexp($2)) {
            return evaluate_sexp($3);
        } else {
            return evaluate_sexp($4);
        }
    }
};

/* Usage */
op()("(if (> 5 3) \"yes\" \"no\")")();  /* Returns "yes" */

4. List Operations

Native LISP list manipulation:

/* LISP list operations */
custom_command = rule '(car' $STR ')' { op(list:$2){
    /* Return first element */
    list_val = evaluate_sexp(list);
    return list_val[0];
} };

custom_command = rule '(cdr' $STR ')' { op(list:$2){
    /* Return rest of list */
    list_val = evaluate_sexp(list);
    return list_val.range(1, list_val.len());
} };

custom_command = rule '(cons' $STR $STR ')' { op(element:$2, list:$3){
    /* Add element to front of list */
    element_val = evaluate_sexp(element);
    list_val = evaluate_sexp(list);
    result = [element_val];
    result += list_val;
    return result;
} };

/* Usage */
op()('(car "(1 2 3)")')();  /* Returns 1 */
op()('(cdr "(1 2 3)")')();  /* Returns [2, 3] */
op()('(cons "0" "(1 2 3)")')();  /* Returns [0, 1, 2, 3] */

Example LISP Syntax Implementation

/* Initialize custom_command and custom_function for LISP syntax */
custom_command = rule '(' $STR $STR $STR ')' {op(function:$2,arg1:$3,arg2:$4){
    /* Evaluate S-expression - NO MANUAL PARSING */
    result = lisp_eval(function, [arg1, arg2]);
    return result;
}};

/* S-expressions with single argument */
custom_command = rule '(' $STR $STR ')' {op(function:$2,arg1:$3){
    /* Evaluate S-expression - NO MANUAL PARSING */
    result = lisp_eval(function, [arg1]);
    return result;
}};

/* S-expressions with three arguments */
custom_command ++= rule '(' $STR $STR $STR $STR ')' {op(function:$2,arg1:$3,arg2:$4,arg3:$5){
    /* Evaluate S-expression - NO MANUAL PARSING */
    result = lisp_eval(function, [arg1, arg2, arg3]);
    return result;
}};

/* Function definition with native grammar */
custom_command ++= rule '(defun' $STR '(' $STR $STR ')' $STR ')' {op(name:$2,param1:$4,param2:$5,body:$7){
    /* Store function definition - NO MANUAL PARSING */
    $global.lisp_functions[name] = {
        params: [param1, param2],
        body: body
    };
    return name;
}};

/* Function definition with single parameter */
custom_command ++= rule '(defun' $STR '(' $STR ')' $STR ')' {op(name:$2,param1:$4,body:$6){
    /* Store function definition - NO MANUAL PARSING */
    $global.lisp_functions[name] = {
        params: [param1],
        body: body
    };
    return name;
}};

/* Variable assignment with native grammar */
custom_command ++= rule '(setq' $STR $STR ')' {op(var:$2,value:$3){
    /* Set variable - NO MANUAL PARSING */
    evaluated_value = evaluate_sexp(value);
    $global.lisp_vars[var] = evaluated_value;
    return evaluated_value;
}};

/* Conditional expression with native grammar */
custom_command ++= rule '(if' $STR $STR $STR ')' {op(condition:$2,then:$3,else:$4){
    /* Evaluate conditional - NO MANUAL PARSING */
    cond_result = evaluate_sexp(condition);
    if (cond_result) {
        return evaluate_sexp(then);
    } else {
        return evaluate_sexp(else);
    };
}};

/* List operations with native grammar */
custom_command ++= rule '(list' $STR ')' {op(elem1:$2){
    /* Create list with single element - NO MANUAL PARSING */
    return [elem1];
}};

custom_command ++= rule '(list' $STR $STR ')' {op(elem1:$2,elem2:$3){
    /* Create list - NO MANUAL PARSING */
    return [elem1, elem2];
}};

custom_command ++= rule '(list' $STR $STR $STR ')' {op(elem1:$2,elem2:$3,elem3:$4){
    /* Create list with three elements - NO MANUAL PARSING */
    return [elem1, elem2, elem3];
}};

/* List access operations */
custom_command ++= rule '(car' $STR ')' {op(list_expr:$2){
    /* Get first element - NO MANUAL PARSING */
    list_val = evaluate_sexp(list_expr);
    if (list_val.type() == $LIST) {
        return list_val[0];
    };
}};

custom_command ++= rule '(cdr' $STR ')' {op(list_expr:$2){
    /* Get rest of list - NO MANUAL PARSING */
    list_val = evaluate_sexp(list_expr);
    if (list_val.type() == $LIST) {
        return list_val.range(1, list_val.len());
    };
}};

custom_command ++= rule '(cons' $STR $STR ')' {op(element:$2,list_expr:$3){
    /* Construct list - NO MANUAL PARSING */
    element_val = evaluate_sexp(element);
    list_val = evaluate_sexp(list_expr);
    if (list_val.type() == $LIST) {
        result = [element_val];
        result += list_val;
        return result;
    };
}};

Key Point: The | operator adds to existing rules rather than replacing them, allowing multiple LISP syntax patterns to coexist.

Usage Examples

Basic Arithmetic

/* Simple arithmetic */
op()("(+ 1 2 3 4 5)")();  /* Returns 15 */
op()("(* 2 3 4)")();      /* Returns 24 */
op()("(+ (* 2 3) (* 4 5))")();  /* Returns 26 */

List Operations

/* List creation and manipulation */
op()('(list "1" "2" "3" "4" "5")')();  /* Returns ["1", "2", "3", "4", "5"] */
op()('(car "(1 2 3)")')();  /* Returns 1 */
op()('(cdr "(1 2 3)")')();  /* Returns [2, 3] */
op()('(cons "0" "(1 2 3)")')();  /* Returns [0, 1, 2, 3] */

Function Definition

/* Define and use functions */
op()("(defun square (x) (* x x))")();
op()("(square 5)")();  /* Returns 25 */

op()("(defun factorial (n) (if (= n 0) 1 (* n (factorial (- n 1)))))")();
op()("(factorial 5)")();  /* Returns 120 */

Variables and Conditionals

/* Variable assignment and conditionals */
op()("(setq x 10)")();  /* Sets x to 10 */
op()("(if (> x 5) \"large\" \"small\")")();  /* Returns "large" */

Integration with Grapa Features

1. Native List Operations

LISP integration leverages Grapa's native list capabilities:

/* Combine LISP with native Grapa */
lisp_result = op()("(list 1 2 3 4 5)")();
grapa_result = lisp_result.map(op(x) { x * 2 });  /* Native Grapa map */
final_result = op()("(cons 0 " + grapa_result + ")")();  /* Back to LISP */

2. Functional Programming

LISP's functional style works naturally with Grapa:

/* Functional composition */
numbers = op()("(list 1 2 3 4 5)")();
squares = numbers.map(op(x) { x * x });  /* Grapa functional */
sum = op()("(+ " + squares.join(" ") + ")")();  /* LISP sum */

3. Metaprogramming

LISP's code-as-data philosophy aligns with Grapa's executable BNF:

/* Generate LISP code dynamically */
generate_factorial = op(n) {
    if (n <= 1) {
        return "(defun factorial (n) 1)";
    } else {
        return "(defun factorial (n) (* n (factorial (- n 1))))";
    };
};

/* Execute generated code */
op()(generate_factorial(5))();

Advanced Features

1. Macros

Implement LISP-style macros for code transformation:

/* Macro definition */
custom_command = rule '(defmacro' $STR '(' $STR* ')' $STR* ')' { 
    op(name:$2, params:$4, body:$6){
        $global.lisp_macros[$2] = {
            params: $4,
            body: $6
        };
        return "Macro " + $2 + " defined";
    }
};

/* Usage */
op()("(defmacro when (condition body) (if condition body nil))")();
op()("(when (> 5 3) (print \"condition is true\"))")();

2. Higher-Order Functions

Implement LISP's functional programming features:

/* Map function */
custom_command = rule '(map' $STR $STR ')' { op(func:$2, list:$3){
    return evaluate_sexp(list).map(op(x) {
        op()("(" + func + " " + x + ")")();
    });
} };

/* Usage */
op()("(map square (list 1 2 3 4 5))")();  /* Returns [1, 4, 9, 16, 25] */

3. Recursive Functions

Demonstrate LISP's recursive capabilities:

/* Recursive list processing */
op()("(defun length (lst) (if (null lst) 0 (+ 1 (length (cdr lst)))))")();
op()("(length (list 1 2 3 4 5))")();  /* Returns 5 */

Best Practices

1. Error Handling

Implement robust error handling for LISP expressions:

/* Safe evaluation */
safe_lisp_eval = op(expr) {
    try {
        return op()(expr)();
    } catch (error) {
        return "LISP Error: " + error;
    };
};

2. Performance Optimization

Use Grapa's native operations when possible:

/* Optimize list operations */
optimized_car = op(list) {
    if (type(list) == $LIST) {
        return list[0];  /* Use native access */
    } else {
        return op()("(car " + list + ")")();  /* Fallback to LISP */
    };
};

3. Integration Patterns

Combine LISP and Grapa effectively:

/* Hybrid approach */
process_data = op(data) {
    /* Use LISP for symbolic processing */
    lisp_result = op()("(process-symbolic " + data + ")")();

    /* Use Grapa for numerical operations */
    grapa_result = lisp_result.map(op(x) { x * 2 });

    /* Return to LISP for final formatting */
    return op()("(format-result " + grapa_result + ")")();
};

Use Cases

1. Educational Programming

  • Teaching LISP concepts using Grapa's modern interface
  • Demonstrating functional programming principles
  • Showing the relationship between LISP and Grapa

2. Symbolic Computation

  • Mathematical expression processing
  • Code generation and transformation
  • Rule-based systems

3. Prototyping

  • Rapid language feature testing
  • Algorithm experimentation
  • Educational tool development

4. Legacy System Integration

  • LISP code migration to Grapa
  • Hybrid LISP/Grapa applications
  • Gradual modernization of LISP systems

Future Enhancements

1. Advanced LISP Features

  • CLOS-style object system
  • Advanced macro system with gensym
  • Stream processing capabilities
  • Lazy evaluation support

2. Performance Improvements

  • Compiled LISP functions
  • Optimized list operations
  • Memory management for large expressions
  • Parallel evaluation support

3. Tooling Integration

  • LISP syntax highlighting
  • Interactive REPL with history
  • Debugging tools for LISP code
  • Code analysis and optimization

Conclusion

Grapa's LISP integration demonstrates the language's ability to implement its own inspiration while providing modern enhancements. This integration showcases:

  • Natural language relationships - Grapa implementing LISP concepts
  • Metaprogramming power - Dynamic syntax and code generation
  • Educational value - Teaching LISP through modern tools
  • Practical applications - Symbolic computation and prototyping

The LISP integration serves as both a tribute to Grapa's heritage and a demonstration of its unique capabilities in language implementation and metaprogramming.