Merustmar

A Myanmar (Burmese) scripting language interpreter written in Rust.

Status: In development. Keywords and syntax may change without notice. Not yet stable for production use.

Overview

Merustmar is a dynamic, interpreted language that utilizes Myanmar script keywords and punctuation. It is implemented as a tree-walking interpreter, featuring a Pratt parser and a Unicode-aware lexer. The language supports standard programming constructs—such as variables, functions, and complex data types—and includes a specialized set of built-in functions for terminal manipulation (TUI).

The project is a learning exercise inspired by Writing an Interpreter in Go (Thorsten Ball), adapted for the Rust ecosystem and localized for the Myanmar language.

Features

Core Language

• Variable Bindings: Single declarations (ထား), multi-variable declarations (လို့ထား), and reassignment (x = value).
• Data Types: Integers, Floats, Booleans, Strings, Arrays, and Hashes (Key-Value pairs).
• Myanmar Digits: Native support for Myanmar numerals (၀–၉) as integer literals (e.g. ၅ ခါပတ် { ... }).
• Arithmetic and Logic:
  • Operators: +, -, *, /, %
  • Comparisons: ==, !=, <, >
  • Boolean Logic: !, &&, ||
• String Operations: Concatenation (+), equality (==/!=), and escape sequences (\n, \t, \\, \").
• Control Flow:
  • Conditionals: တကယ်လို့ (if) and မဟုတ်ရင် (else).
  • Functions: First-class functions defined with ဖန်ရှင် (fn), supporting closures.
  • Return values: ဒါယူ (return).
• Looping Constructs:
  • Infinite Loops: ပတ် { ... }
  • While-style Loops: ပတ် condition { ... }
  • Fixed-iteration Loops: N ခါပတ် { ... } (accepts both Arabic and Myanmar digits)
• Collections: Array indexing (array[index]), Hash literals ({"key": value}), and Hash access (hash["key"]).

Terminal User Interface (TUI)

Merustmar integrates with crossterm to allow the creation of terminal-based applications.

• Coordinate Printing: Print text at specific X/Y coordinates.
• Screen Management: Initialize alternate screens, clear screens, and flush buffers.
• UI Elements: Built-in support for drawing centered borders and boxes.
• Input Handling: Blocking and non-blocking key polling.

Keywords (Myanmar)

Keyword	Meaning
ထား	let
လို့ထား	multi-let separator
ဖန်ရှင်	fn
တကယ်လို့	if
မဟုတ်ရင်	else
ဒါယူ	return
မှန်	true
မှား	false
ပတ်	loop
ခါပတ်	times-loop marker
ရေး	print (built-in)

Built-in Functions

General Utilities

• ရေး(val, ...): Prints values to the console. Accepts multiple arguments.
• len(obj): Returns length of strings or arrays.
• first(arr), last(arr), rest(arr): Array element access and slicing.
• push(arr, val): Appends an element to an array.
• sleep(ms): Pauses execution for the given milliseconds.
• rand(min, max): Generates a random integer (inclusive on both ends).
• now_ms(): Returns the current Unix timestamp in milliseconds.

Input and Type Checking

• input(prompt?): Reads a line of input from stdin. Optionally accepts a prompt string.
• is_string(val): Returns true if the value is a string.
• is_int(val): Returns true if the value is an integer or a string parseable as an integer.
• is_double(val): Returns true if the value is a float or a string parseable as a float.
• to_integer(val): Converts an integer, float, or numeric string to an integer.
• to_double(val): Converts a float, integer, or numeric string to a float.

Terminal Control

• terminal_init(): Initializes raw mode and the alternate screen.
• terminal_end(): Cleans up and restores the terminal.
• clear(): Clears the terminal screen.
• terminal_size(): Returns the current terminal width and height as [width, height].
• print_at(x, y, text): Prints text at a specific location.
• print_at_center(x, y, cols, rows, text): Centers text within a specified box.
• draw_border(cols, rows): Draws a centered border.
• flush(): Flushes the terminal output buffer.
• read_key(): Blocks until a key is pressed, returns the key as a string.
• poll_key(timeout_ms): Checks for key input without blocking indefinitely. Returns null on timeout.

Building

Ensure you have a stable Rust toolchain (1.70+ recommended).

git clone https://github.com/codewiththiha/merustmar.git
cd merustmar
cargo build --release

Usage

REPL

Start the interactive Read-Eval-Print Loop:

cargo run -- --input

Example session:

>> ထား x = 10။
>> ထား y = 20။
>> x + y
30
>> ရေး("မင်္ဂလာပါ")
မင်္ဂလာပါ

Run a Script

Execute a source file with the .mrm extension:

cargo run -- --run examples/hello.mrm

Project Structure

src/
├── ast.rs           # Abstract Syntax Tree nodes
├── builtins.rs      # Standard and Terminal built-in functions
├── environment.rs   # Variable environment and scoping
├── evaluator.rs     # Tree-walking evaluation logic
├── lexer.rs         # Unicode-aware lexer (supports Myanmar script)
├── main.rs          # CLI entry point
├── object.rs        # Object system and type definitions
├── parser.rs        # Pratt parser implementation
├── repl.rs          # Interactive shell logic
├── runner.rs        # Script file execution logic
├── token.rs         # Token definitions and keyword mapping
└── terminal.rs      # Low-level TUI wrappers (crossterm)

License

This project is licensed under the MIT License.

Acknowledgements

• Inspired by the Monkey programming language and the book Writing an Interpreter in Go by Thorsten Ball.
• Implemented using Rust's ownership model, pattern matching, and algebraic data types.