Hython Interpreter

Hython is a Python-style scripting interpreter written in Haxe.
 (Think hscript, but with Python syntax and semantics)

It’s designed for: embedding scripting into Haxe projects game modding configuration DSLs runtime logic without recompiling

⚠️ This is not CPython. It’s a Python-like language implemented on top of Haxe.

Usage

Basic Usage

import paopao.hython.Parser;
import paopao.hython.Interp;

// Simple execution
var code = "
def greet(name):
    return 'Hello, ' + name + '!'

print(greet('World'))
";

var parser = new Parser();
var expr = parser.parseString(code);
var interp = new Interp();
interp.execute(expr);

Advanced Usage - Calling Specific Functions

// Define your Python-like code
var code = "
def add(a, b):
    return a + b

def multiply(a, b):
    return a * b

def main(x, y):
    sum = add(x, y)
    product = multiply(x, y)
    print('Sum:', sum)
    print('Product:', product)
    return {'sum': sum, 'product': product}
";

// Parse and execute to define functions
var parser = new Parser();
var expr = parser.parseString(code);
var interp = new Interp();
interp.execute(expr);

// Call specific functions with arguments
var result = interp.calldef("main", [10, 5]);
// Output:
// Sum: 15
// Product: 50

// Call individual functions
var sum = interp.calldef("add", [7, 3]);      // Returns 10
var product = interp.calldef("multiply", [4, 6]); // Returns 24

Setting Variables from Haxe

var interp = new Interp();

// Set variables before executing code
interp.variables.set("myValue", 42);
interp.variables.set("config", {debug: true, version: "1.0"});

var code = "
def process():
    print('Value:', myValue)
    print('Debug mode:', config['debug'])
    return myValue * 2
";

var parser = new Parser();
interp.execute(parser.parseString(code));
var result = interp.calldef("process", []); // Returns 84

Error Handling

var interp = new Interp();

// Set custom error handler
interp.errorHandler = function(error) {
    trace("Script error: " + error);
    // Handle error gracefully
};

// Configure interpreter
interp.maxDepth = 100;  // Maximum recursion depth
interp.allowStaticAccess = true;  // Allow static access
interp.allowClassResolve = true;  // Allow class instantiation

var code = "
def risky_function():
    # This might cause an error
    return undefined_variable
";

try {
    var parser = new Parser();
    interp.execute(parser.parseString(code));
    interp.calldef("risky_function", []);
} catch (e:Dynamic) {
    trace("Caught error: " + e);
}

Features

Python-Style Syntax

• def function definitions with default arguments
• Python operators: and, or, not, in, not in, is, is not
• List comprehensions: [x * 2 for x in range(10) if x % 2 == 0]
• Dictionary comprehensions: {x: x**2 for x in range(5)}
• Slicing: my_list[1:5], my_string[::2]
• Tuple support: (1, 2, 3) (it have bug I know, but it's not fixed yet at Tuple Unpacking)

Built-in Functions

Hython includes Python-compatible built-in functions:

Type Conversion:

• int(), float(), str(), bool()
• list(), dict(), type()

Numeric Functions:

• abs(), min(), max(), sum()
• round(), pow(), sqrt()

Sequence Functions:

• len(), range(), enumerate()
• sorted(), reversed(), zip()

Logic Functions:

• any(), all(), isinstance()

String Functions:

• ord(), chr()

I/O Functions:

• print()

Example: Complete Script

var code = "
# Calculate fibonacci numbers
def fibonacci(n):
    if n <= 1:
        return n
    return fibonacci(n - 1) + fibonacci(n - 2)

def main(count):
    results = [fibonacci(i) for i in range(count)]
    print('Fibonacci sequence:', results)
    return results

# Helper function
def sum_fibonacci(count):
    return sum([fibonacci(i) for i in range(count)])
";

var parser = new Parser();
var interp = new Interp();
interp.execute(parser.parseString(code));

// Call functions
var sequence = interp.calldef("main", [10]);
var total = interp.calldef("sum_fibonacci", [10]);

trace("Sequence: " + sequence);  // [0, 1, 1, 2, 3, 5, 8, 13, 21, 34]
trace("Sum: " + total);           // 88

API Reference

Interp Class

Methods

• new() - Create a new interpreter instance
• execute(expr:Expr):Dynamic - Execute parsed expression tree
• calldef(name:String, args:Array<Dynamic>):Dynamic - Call a defined function by name
• getdef(name:String):Dynamic - Get a defined function by name
• setVar(name:String, value:Dynamic):Dynamic - Set a variable
• getVar(name:String):Dynamic - Get a variable

Properties

• variables:Map<String, Dynamic> - Global variable storage
• errorHandler:Error->Void - Custom error handler
• maxDepth:Int - Maximum recursion depth (default: 100)
• allowStaticAccess:Bool - Allow static field access (default: true)
• allowClassResolve:Bool - Allow class instantiation (default: true)

Parser Class

Methods

• new() - Create a new parser instance
• parseString(code:String):Expr - Parse Python-like code into expression tree

Integration Examples

Game Modding Example

class ModSystem {
    var interp:Interp;

    public function new() {
        interp = new Interp();
        // Expose game API to scripts
        interp.variables.set("game", GameAPI.instance);
    }

    public function loadMod(scriptPath:String) {
        var code = sys.io.File.getContent(scriptPath);
        var parser = new Parser();
        interp.execute(parser.parseString(code));
    }

    public function callModFunction(name:String, args:Array<Dynamic>) {
        return interp.calldef(name, args);
    }
}

// In your mod script (Python-like syntax):
/*
def on_player_hit(damage, enemy):
    game.show_damage(damage)
    if game.player.health <= 0:
        game.game_over()
    return True

def on_level_complete(score):
    bonus = score * 1.5
    game.add_bonus(bonus)
    return bonus
*/

Configuration DSL Example

var configScript = "
def setup():
    return {
        'window': {
            'width': 1280,
            'height': 720,
            'fullscreen': False
        },
        'audio': {
            'master_volume': 0.8,
            'music_volume': 0.6
        }
    }
";

var parser = new Parser();
var interp = new Interp();
interp.execute(parser.parseString(configScript));
var config = interp.calldef("setup", []);

Origin

This project is a fork of NebulaStellaNova’s pythonscript.
I saw it, liked the idea, and decided to push it further. :3

License

MIT