Quetite

Source

Quetite is a small interpreted scripting language with a friendly, Ruby-like syntax, dynamic typing, and an stdlib of native helpers. It is implemented as a classic three-stage interpreter (lexer -> parser -> evaluator) in Rust.

println("Hello Quetite!")

[!WARNING]
Quetite is still a WIP (work in progress) language. Expect breaking changes!

Features

[x] Easy and familiar scripting language syntax, no semicolons, no indentation rules
[x] Fully dynamic type system (with types like Bool, Num, Str etc...)
[x] First class functions (Callable type) and objects with constructors, static and bound methods (Obj type)
[x] Fully dynamic lists and dictionaries (List and Dict types)
[x] Internal prototype methods on primitives (Str.len(), List.push(), Dict.keys(), etc.)
[x] Familiar control flow: if/else, while, for over iterables, match
[x] Friendly and easy to understand errors!
[x] Runtime error handling system via throw and try/catch/ensure
[x] Misc scripting features such as: ranges (.. and ..= operators), list/string slicing (str[a..b]), nullish coalescing (a ?? b), power (a**b) and ternary (cond ? a : b) operators
[x] Truthiness rules (false, Null, 0 are falsy; everything else is truthy)
[x] Powerful and extensive stdlib (Sys, Math, Rand, Term etc.)
[x] Ability to include other scripts inside a script via use
[x] Fully interactive REPL with interactive help command
[ ] Ratatui bindings for the stdlib to create fun TUI apps! (half implemented, full implementation coming soon!)
[ ] Processing/p5.js like simple creative coding and graphics API for the stdlib to create fun games and creative programs! (half implemented, full implementation coming soon!)

Quick Start

Prereqs: Rust toolchain installed via rustup.

Build and run a script:

cargo run path/to/script.qte

Run the example snake.qte:

cargo run examples/snake.qte

Run the interactive REPL:

cargo run

Use the help command inside the REPL to interactively explore "The Quetite Language Reference" and "API Reference" documentations. Also check out the examples folder to see other examples!

Example Rock-Paper-Scissors Game in Quetite

println("Rock Paper Scissors in Quetite!")

var moves = ["rock", "paper", "scissors"]
var beats = {
    "rock": "scissors",
    "paper": "rock",
    "scissors": "paper"
}

while true do
    print("\nMake your move: ")
    var user = read()

    if user == "q" break
    if !moves.contains(user) do
        print("Invalid move! Valid moves are: ")
        println(moves)
        continue
    end

    var computer = Rand.list(moves)

    println("\nYour move: " + user)
    println("Computer's move: " + computer)

    if beats[computer] == user println("\nComputer wins!")
    if beats[user] == computer println("\nYou win!")
    if user == computer println("\nIt's a draw!")
end

Quetite at a Glance

See "The Quetite Language Reference" for a full list and detailed explanations of Quetite's features.

Values & Prototypes
type(), type_of(), type_check() on any value; conversions via to_*() helpers.
Strings
Indexing and slicing; len(), repeat(n), and terminal color/style helpers.
Lists
Dynamic arrays with len(), push(), pop(), insert(i, v), remove(i), first(), last(), contains(v).
Dicts
Hash maps keyed by Null/Bool/Num/Str; len(), contains(k), insert(k, v), remove(k), get(k), keys(), values().
Control Flow
if/else, while, for value, index in iterable, match, ternary cond ? a : b, ranges a..b and a..=b with optional step, slicing with ranges.
Errors
try/catch/ensure and throw; internal error types include TypeErr, NameErr, ArityErr, ValueErr, NativeErr, IOErr, UserErr.
Objects & Functions
First-class functions; objects with optional init() constructor, static methods, and bound methods using self.

Repository Layout

examples - example Quetite scripts
src/lexer - tokenizer
src/parser - recursive descent parser producing AST
src/evaluator - tree-walk interpreter and stdlib natives
REFERENCE.md - full language reference

Tags: language interpreter