🐒 MKS

Small experimental scripting language + interpreter in C.

Contents

• Feature overview
• Hello, MKS
• Language tour
• Entities & extend
• Imports & stdlib
• Watch / defer
• CLI
• Repo layout
• Docs

Feature overview

• Expressions: numbers, strings, arrays, indexing.
• Control flow: if/else, while, for, repeat, break, continue.
• Functions & recursion: fnc name(args) -> ... <-, return.
• Swap operator: a <--> b; (fast in-place).
• Defer & watch/on change.
• Entities (lightweight objects) + methods; extend built-ins (array/string).
• Imports with built-in std path (std/math).
• Friendly errors with hints; recursion-depth guard.
• Simple mark/sweep GC; sanitizer-friendly build.

Hello, MKS

using "std/math";

var x =: 10;
watch x;
on change x -> Writeln("x changed"); <-

x =: square(x);     // triggers watcher
Writeln("result:", x);

Language tour

Variables & swap

var a =: 1;
var b =: 2;
a <--> b;          // swap

Control flow

if (a > 0) -> Writeln("positive"); <-
while (a < 5) -> a =: a + 1; <-
for (var i =: 0; i < 3; i =: i + 1) -> Writeln(i); <-
repeat 3 -> Writeln("ping"); <-
repeat i in 3 -> Writeln(i); <-

Functions

fnc add(a, b) ->
    return a + b;
<-
Writeln(add(2, 3));

Tests

test "math add" ->
    expect(1 + 1 ?= 2);
<-

Entities & extend

entity User(name) ->
    init -> self.name =: name; <-
    method hi() -> Writeln("Hi ", self.name); <-
<-

var u =: User("Ann");
u.hi();

extend array ->
    method sum() ->
        var s =: 0; var i =: 0;
        while (i < self.len()) -> s =: s + self[i]; i =: i + 1; <-
        return s;
    <-
<-

Writeln([1,2,3].sum()); // 6

Imports & stdlib

using "path/to/file";   // .mks optional
using "std/math";       // built-in path

Resolution: current file dir → CWD → installed std path. A module runs once (duplicate/nested imports are skipped).

std/math.mks (pure MKS):

using "std/math";
Writeln(abs(-5));
Writeln(square(4));
Writeln(min(10, 3));
Writeln(max(10, 3));

Watch / defer

watch x;
on change x -> Writeln("x changed to ", x); <-

defer -> Writeln("leaving scope"); <-

on change must be registered before the assignment you want to observe.

CLI

mks <file.mks>   # run file
mks --repl       # interactive REPL
mks --version
mks --help

Repo layout

• Lexer/ – tokens
• Parser/ – AST + parsing
• Eval/ – evaluation
• Runtime/ – values, operators, modules, errors
• env/ – variable scopes
• GC/ – garbage collector
• std/ – bundled stdlib (std/math.mks)
• examples/ – runnable samples
• docs/ – reference / guides
• tests/ – golden tests (./tests.sh)

Docs

• docs/REFERENCE.md — quick reference (syntax & examples).
• docs/USER_GUIDE.md — step-by-step guide (entities, extend, watch/defer, repeat, swap).

Status

Active, experimental. APIs may change. Friendly errors should point to the fix; if not, please open an issue.

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