lua2wasm/runtime/playground.html at main · rhmoller/lua2wasm

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<!doctype html>

<title>lua2wasm playground</title>

<!-- Favicon: the official Lua logo (http://lua-users.org/wiki/LuaLogo),

inlined as base64 PNGs at 16/32/64 px so the page stays self-contained

(the GitHub Pages deploy stages a flat dist/ with no asset copy step).

The browser picks the size closest to its render target. -->

<style>

/* Catppuccin palettes (https://github.com/catppuccin/catppuccin).

Two flavours wired to the same variable names so the rest of the

stylesheet — and the CodeMirror theme below — only references

--ctp-* and just follows whichever block is active. Mocha is the

default; setting `data-theme="light"` on <html> swaps to Latte. */

:root, html[data-theme="dark"] {

color-scheme: dark;

--ctp-rosewater: #f5e0dc;

--ctp-flamingo: #f2cdcd;

--ctp-pink: #f5c2e7;

--ctp-mauve: #cba6f7;

--ctp-red: #f38ba8;

--ctp-maroon: #eba0ac;

--ctp-peach: #fab387;

--ctp-yellow: #f9e2af;

--ctp-green: #a6e3a1;

--ctp-teal: #94e2d5;

--ctp-sky: #89dceb;

--ctp-sapphire: #74c7ec;

--ctp-blue: #89b4fa;

--ctp-lavender: #b4befe;

--ctp-text: #cdd6f4;

--ctp-subtext1: #bac2de;

--ctp-subtext0: #a6adc8;

--ctp-overlay2: #9399b2;

--ctp-overlay1: #7f849c;

--ctp-overlay0: #6c7086;

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--ctp-surface1: #45475a;

--ctp-surface0: #313244;

--ctp-base: #1e1e2e;

--ctp-mantle: #181825;

--ctp-crust: #11111b;

}

html[data-theme="light"] {

color-scheme: light;

--ctp-rosewater: #dc8a78;

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--ctp-red: #d20f39;

--ctp-maroon: #e64553;

--ctp-peach: #fe640b;

--ctp-yellow: #df8e1d;

--ctp-green: #40a02b;

--ctp-teal: #179299;

--ctp-sky: #04a5e5;

--ctp-sapphire: #209fb5;

--ctp-blue: #1e66f5;

--ctp-lavender: #7287fd;

--ctp-text: #4c4f69;

--ctp-subtext1: #5c5f77;

--ctp-subtext0: #6c6f85;

--ctp-overlay2: #7c7f93;

--ctp-overlay1: #8c8fa1;

--ctp-overlay0: #9ca0b0;

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--ctp-surface1: #bcc0cc;

--ctp-surface0: #ccd0da;

--ctp-base: #eff1f5;

--ctp-mantle: #e6e9ef;

--ctp-crust: #dce0e8;

}

* { box-sizing: border-box; }

html, body { height: 100%; margin: 0; }

body {

display: grid;

grid-template-rows: auto auto 1fr auto;

font: 14px/1.4 system-ui, sans-serif;

background: var(--ctp-base);

color: var(--ctp-text);

}

#intro {

padding: .55em 1em; font-size: 13px; line-height: 1.5;

color: var(--ctp-subtext1);

background: var(--ctp-mantle);

border-bottom: 1px solid var(--ctp-surface0);

}

#intro strong { color: var(--ctp-text); }

#intro a { color: var(--ctp-sapphire); text-decoration: none; }

#intro a:hover { text-decoration: underline; }

header {

display: flex; align-items: center; gap: 1em;

padding: .6em 1em;

background: var(--ctp-mantle);

border-bottom: 1px solid var(--ctp-surface0);

}

header h1 { font-size: 1em; margin: 0; color: var(--ctp-subtext0); font-weight: 500; }

header h1 a { color: var(--ctp-lavender); text-decoration: none; }

header h1 a:hover { text-decoration: underline; }

button, select {

background: var(--ctp-surface0); color: var(--ctp-text);

border: 1px solid var(--ctp-surface1);

padding: .4em .9em; border-radius: 6px; font: inherit; cursor: pointer;

}

button:hover, select:hover { background: var(--ctp-surface1); border-color: var(--ctp-surface2); }

button[disabled] { opacity: .4; cursor: default; }

main {

/* Two flexible columns with a draggable splitter between them. The

JS sets --split-left (a percent like "42%") on pointermove; the

fr units fall back to the initial 50/50 split before any drag. */

display: grid;

grid-template-columns: minmax(160px, var(--split-left, 1fr))

6px

minmax(160px, 1fr);

min-height: 0;

border-bottom: 1px solid var(--ctp-surface0);

}

#editor-host {

overflow: auto;

background: var(--ctp-base);

}

.cm-editor { height: 100%; }

.cm-scroller { font: 13px/1.5 "JetBrains Mono", ui-monospace, monospace; }

#splitter {

background: var(--ctp-surface0);

cursor: col-resize;

/* Widen the hit target without enlarging the visible bar — a

transparent pseudo-element extends the grabbable area to ~10px. */

position: relative;

touch-action: none;

}

#splitter::before {

content: ""; position: absolute; inset: 0 -3px;

}

#splitter:hover,

#splitter.dragging { background: var(--ctp-surface1); }

/* While dragging: kill text selection across the whole window and

keep the resize cursor regardless of what the pointer is over. */

body.splitter-dragging { cursor: col-resize; user-select: none; }

#out {

margin: 0; padding: 1em; overflow: auto;

font: 13px/1.5 ui-monospace, monospace;

background: var(--ctp-crust); color: var(--ctp-text);

white-space: pre-wrap;

}

/* Scrollbars: blend into the Catppuccin Mocha surface tones rather

than the browser default light-on-dark.

Firefox honours scrollbar-color; Chromium/Safari use the webkit

pseudo-elements. Both target the editor (.cm-scroller) and the

output panel (#out). */

.cm-scroller, #out {

scrollbar-width: thin;

scrollbar-color: var(--ctp-surface1) transparent;

}

.cm-scroller::-webkit-scrollbar,

#out::-webkit-scrollbar {

width: 10px; height: 10px;

}

.cm-scroller::-webkit-scrollbar-track,

#out::-webkit-scrollbar-track {

background: transparent;

}

.cm-scroller::-webkit-scrollbar-thumb,

#out::-webkit-scrollbar-thumb {

background: var(--ctp-surface1);

border: 2px solid transparent; /* fakes inset padding around the thumb */

border-radius: 6px;

background-clip: padding-box;

}

.cm-scroller::-webkit-scrollbar-thumb:hover,

#out::-webkit-scrollbar-thumb:hover {

background: var(--ctp-surface2);

background-clip: padding-box;

}

.cm-scroller::-webkit-scrollbar-corner,

#out::-webkit-scrollbar-corner {

background: transparent;

}

/* WAT viewer: codegen tags each region with `;; @@SECTION:name@@`;

showWat() splits on those and emits one of these per section. The

runtime regions collapse by default since they're ~5000 lines of

shared infrastructure that doesn't change with the user's code. */

.wat-section { margin: 0 0 .25em 0; }

.wat-section > summary {

list-style: none;

cursor: pointer; user-select: none;

padding: .25em .6em; margin: 0;

background: var(--ctp-surface0); color: var(--ctp-subtext1);

border-radius: 4px;

font: 12px/1.4 system-ui, sans-serif;

display: flex; align-items: center; gap: .6em;

}

.wat-section > summary::-webkit-details-marker { display: none; }

.wat-section > summary::before {

content: "▸"; display: inline-block; width: 1em;

color: var(--ctp-overlay1); transition: transform .1s;

}

.wat-section[open] > summary::before { transform: rotate(90deg); }

.wat-section > summary .wat-name { color: var(--ctp-text); font-weight: 500; }

.wat-section > summary .wat-meta { color: var(--ctp-overlay1); font-size: 11px; margin-left: auto; }

.wat-section > pre {

margin: 0; padding: .4em .8em;

background: var(--ctp-base); color: var(--ctp-subtext1);

border-left: 2px solid var(--ctp-surface1);

border-radius: 0 0 4px 4px;

overflow-x: auto;

font: 12px/1.45 "JetBrains Mono", ui-monospace, monospace;

}

/* Highlight the "user code" section — that's the part the dev cares about. */

.wat-section[data-section="user-code"] > summary {

background: var(--ctp-surface1);

}

.wat-section[data-section="user-code"] > pre {

border-left-color: var(--ctp-sapphire);

color: var(--ctp-text);

}

/* WAT syntax tokens — palette mirrors the editor's Lua highlighter so

keywords/strings/comments/numbers all look the same on both sides. */

.wat-comment { color: var(--ctp-overlay1); font-style: italic; }

.wat-string { color: var(--ctp-green); }

.wat-number { color: var(--ctp-peach); }

.wat-keyword { color: var(--ctp-mauve); } /* func, param, result, etc. */

.wat-instr { color: var(--ctp-blue); } /* local.get, call, br_table, etc. */

.wat-type { color: var(--ctp-yellow); } /* i32, f64, anyref, … */

.wat-ident { color: var(--ctp-rosewater); } /* $name */

.wat-paren { color: var(--ctp-overlay2); }

/* A line belonging to a function/global that DCE drops from the final

.wasm. Dimmed + struck through so the surviving module reads clearly;

hover shows why. The opacity also fades the nested syntax spans. */

.wat-dead { opacity: .4; text-decoration: line-through;

text-decoration-color: var(--ctp-overlay0); }

.wat-note { margin: 0 0 .5em 0; color: var(--ctp-overlay1);

font: 12px/1.45 "JetBrains Mono", ui-monospace, monospace; }

/* "hide dead code" toggle next to the Show WAT button. */

#hidedead-label { color: var(--ctp-subtext0); font-size: 13px;

user-select: none; cursor: pointer;

display: inline-flex; align-items: center; gap: .3em; }

#hidedead-label input { vertical-align: middle; cursor: pointer; }

.err { color: var(--ctp-red); }

.info { color: var(--ctp-overlay1); }

.stdin-prompt { color: var(--ctp-sapphire); }

.stdin-input {

background: transparent; border: none; color: var(--ctp-text);

font: inherit; outline: none; min-width: 12em;

caret-color: var(--ctp-rosewater);

}

.stdin-done { color: var(--ctp-sky); }

footer {

padding: .4em 1em; font-size: 12px; color: var(--ctp-overlay1);

background: var(--ctp-mantle);

border-top: 1px solid var(--ctp-surface0);

}

footer code {

background: var(--ctp-surface0); color: var(--ctp-subtext1);

padding: 1px 4px; border-radius: 3px;

}

footer .warn {

background: var(--ctp-surface0); color: var(--ctp-yellow);

padding: 1px 6px; border-radius: 3px;

}

footer a { color: var(--ctp-sapphire); text-decoration: none; }

footer a:hover { text-decoration: underline; }

</style>

<h1><a href="https://github.com/rhmoller/lua2wasm" target="_blank" rel="noopener">lua2wasm</a> playground</h1>

<option value="stack">stack (OO + errors + pcall)</option>

<option value="hello">hello</option>

<option value="fact">factorial</option>

<option value="counter">counter (closure)</option>

<option value="tables">tables</option>

<option value="oo">OOP via metatables</option>

<option value="pcall">pcall</option>

<option value="close"><close> (to-be-closed)</option>

<option value="forloop">for + ipairs</option>

<option value="iter">iterator (closure)</option>

<option value="stdin">interactive (io.read)</option>

<option value="files">files (io.open)</option>

</optgroup>

<option value="s_hello">hello.lua</option>

<option value="s_account">account.lua</option>

<option value="s_bisect">bisect.lua</option>

<option value="s_globals">globals.lua</option>

</optgroup>

<option value="tjdevries">TJ DeVries: Everything You Need To Start Writing Lua</option>

</optgroup>

</select>

<label id="hidedead-label"

title="Show WAT: strike through dead code, or omit it entirely">

<input type="checkbox" id="hidedead"> hide dead code

</label>

<button id="theme-toggle" style="margin-left:auto"

title="Toggle Catppuccin Mocha (dark) / Latte (light)">

</button>

</header>

<strong>lua2wasm</strong> is an ahead-of-time compiler that turns Lua 5.5

source into standalone WebAssembly modules using the WASM-GC,

typed-references, and exception-handling proposals. The compiler itself

runs <em>in this page</em> — your Lua source never leaves the browser.

<a href="https://github.com/rhmoller/lua2wasm" target="_blank" rel="noopener">Source on GitHub →</a>

</aside>

<main>

<div id="splitter" role="separator" aria-orientation="vertical"

tabindex="0" aria-label="Resize panels"></div>

</main>

Pipeline: <code>Lua → lua2wasm (in WASM) → WAT → wat2wasm → WASM-GC → execute</code>

· Runs in any current browser (Chrome 137+, Firefox 131+, Safari 18.4+).

· color theme by <a href="https://catppuccin.com" target="_blank" rel="noopener">catppuccin.com</a>

· build <a id="build-hash" href="https://github.com/rhmoller/lua2wasm/commits/main" target="_blank" rel="noopener"><code>dev</code></a>

</footer>

import { basicSetup, EditorView } from "https://esm.sh/codemirror@6.0.2";

import { StreamLanguage, HighlightStyle,

syntaxHighlighting } from "https://esm.sh/@codemirror/language@6.10.2";

import { lua as luaMode } from "https://esm.sh/@codemirror/legacy-modes@6.4.0/mode/lua";

import { tags as t } from "https://esm.sh/@lezer/highlight@1.2.1";

/* ---- Catppuccin theme via CSS variables ----

* The actual color values live in the :root / [data-theme] blocks at

* the top of this file. Pointing the CodeMirror theme at the same

* --ctp-* vars means a theme toggle just flips html[data-theme]; the

* editor follows along without rebuilding any extension. */

const CTP = new Proxy({}, { get: (_, k) => `var(--ctp-${String(k)})` });

const catppuccinTheme = EditorView.theme({

"&": { color: CTP.text, backgroundColor: CTP.base },

".cm-content": { caretColor: CTP.rosewater },

".cm-cursor, .cm-dropCursor": { borderLeftColor: CTP.rosewater },

"&.cm-focused .cm-selectionBackground, .cm-selectionBackground, .cm-content ::selection": {

backgroundColor: CTP.surface1 + " !important",

".cm-panels": { backgroundColor: CTP.mantle, color: CTP.text },

".cm-panels.cm-panels-top": { borderBottom: "2px solid " + CTP.surface0 },

".cm-panels.cm-panels-bottom": { borderTop: "2px solid " + CTP.surface0 },

".cm-searchMatch": { backgroundColor: CTP.surface2, color: CTP.text },

".cm-searchMatch.cm-searchMatch-selected": { backgroundColor: CTP.surface2 },

/* Tint the active line via a pseudo-element behind CodeMirror's

selection layer (drawSelection paints it at z-index -2, below

.cm-content). An opaque line background would sit in the content

layer and hide the selection on whichever line holds the selection

head — e.g. drag-selecting upward left the top line looking

unselected. z-index -3 keeps the tint below the selection so both

coexist. */

".cm-activeLine": { position: "relative" },

".cm-activeLine::before": {

content: '""', position: "absolute", inset: "0",

backgroundColor: CTP.mantle, zIndex: "-3", pointerEvents: "none",

".cm-selectionMatch": { backgroundColor: CTP.surface1 },

".cm-matchingBracket, .cm-nonmatchingBracket": {

backgroundColor: CTP.surface1, outline: "1px solid " + CTP.overlay0,

".cm-gutters": {

backgroundColor: CTP.base, color: CTP.overlay0,

borderRight: "1px solid " + CTP.surface0,

".cm-activeLineGutter": { backgroundColor: CTP.mantle, color: CTP.lavender },

".cm-foldPlaceholder": { backgroundColor: CTP.surface1, color: CTP.subtext0, border: "none" },

".cm-tooltip": {

backgroundColor: CTP.mantle, color: CTP.text,

border: "1px solid " + CTP.surface0,

".cm-tooltip-autocomplete > ul > li[aria-selected]": {

backgroundColor: CTP.surface1, color: CTP.text,

}, { dark: true });

const luaHighlightStyle = HighlightStyle.define([

{ tag: [t.keyword, t.controlKeyword, t.modifier, t.definitionKeyword], color: CTP.mauve, fontWeight: "500" },

{ tag: t.operatorKeyword, color: CTP.mauve },

{ tag: [t.string, t.special(t.string)], color: CTP.green },

{ tag: t.regexp, color: CTP.red },

{ tag: t.escape, color: CTP.pink },

{ tag: [t.number, t.bool, t.null, t.atom], color: CTP.peach },

{ tag: [t.comment, t.lineComment, t.blockComment], color: CTP.overlay0, fontStyle: "italic" },

{ tag: t.operator, color: CTP.sky },

{ tag: [t.punctuation, t.bracket, t.brace, t.paren], color: CTP.overlay2 },

{ tag: t.variableName, color: CTP.text },

{ tag: t.function(t.variableName), color: CTP.blue },

{ tag: t.function(t.propertyName), color: CTP.blue },

{ tag: t.propertyName, color: CTP.lavender },

{ tag: t.labelName, color: CTP.maroon },

{ tag: t.typeName, color: CTP.yellow },

{ tag: t.namespace, color: CTP.yellow },

{ tag: t.self, color: CTP.red, fontStyle: "italic" },

{ tag: t.invalid, color: CTP.red, textDecoration: "underline" },

]);

import { loadCompiler } from "./lua2wasm-wasm.mjs";

import { InMemoryFs } from "https://esm.sh/just-bash@latest";

import { MATH_FNS, MATH2_FNS,

makeHelpers, BufferedFile,

parseFileMode } from "./host-bindings.mjs";

import { formatFloat, formatScalar, cFormatG, cFormatF, cFormatE } from "./format.mjs";

/* ----- fixture presets ----- */

const PRESETS = {

// AUTO-GENERATED — edit runtime/presets/manifest.json and the

// referenced .lua files, then run `node scripts/bundle-presets.mjs`.

"stack": `-- A "Stack" class — exercises tables, metatables, OO sugar, closures,

-- errors, and pcall in one short program.

local Stack = {} -- a Lua table → a \`$LuaTable\` struct:

Stack.__index = Stack -- array part + open-addressed hash + \`meta\` slot

function Stack.new()

return setmetatable({n = 0}, Stack) -- writes Stack into the struct's \`meta\` field

end -- \`Stack.new\` itself is a \`(ref $LuaClosure)\` =

-- struct (funcref code, upvalue array)

function Stack:push(v) -- \`:\` desugars to \`self\` as the first parameter

self.n = self.n + 1 -- small ints unbox to \`i31ref\` — zero allocation

self[self.n] = v -- integer keys land in the dense array part

end

function Stack:pop()

if self.n == 0 then

error("stack underflow") -- compiles to \`throw $LuaError\` (anyref payload)

end

local v, n = self[self.n], self.n

self[n], self.n = nil, n - 1

return v

end

local s = Stack.new()

s:push("hi"); s:push("from"); s:push("lua2wasm")

-- each string literal materialises once via \`array.new_data\` from a shared data segment

for i = 1, s.n do print(s[i]) end -- numeric \`for\` keeps \`i\` as a raw \`i64\`;

-- the call to \`print\` dispatches via \`call_ref\`

local ok, err = pcall(function() -- \`pcall\` → \`try_table (catch $LuaError ...)\`

for _ = 1, 4 do s:pop() end -- the 4th \`pop\` underflows and throws

end)

print(ok, err) --> false <src>:19: stack underflow

"hello": `print("hello from lua2wasm!")

print(1 + 2)

"fact": `local function fact(n)

if n <= 1 then return 1 end

return n * fact(n - 1)

end

print(fact(10)) -- 3628800

"counter": `local function counter()

local n = 0

local function tick() n = n + 1; return n end

return tick

end

local c = counter()

print(c()) -- 1

print(c()) -- 2

print(c()) -- 3

"tables": `local t = {10, 20, 30, name = "alice"}

print(t[1])

print(t.name)

print(#t)

local nested = {inner = {x = 1, y = 2}}

print(nested.inner.x + nested.inner.y)

"oo": `local Animal = {kind = "animal"}

Animal.speak = function(self) return self.kind .. " speaks" end

local Dog = setmetatable({kind = "dog"}, {__index = Animal})

print(Dog.speak(Dog))

-- vector with __add

local Vec = {}

Vec.__add = function(a, b)

return setmetatable({x = a.x + b.x, y = a.y + b.y}, Vec)

end

local v = setmetatable({x = 1, y = 2}, Vec) + setmetatable({x = 10, y = 20}, Vec)

print(v.x); print(v.y)

"pcall": `local function safediv(a, b)

if b == 0 then error("division by zero") end

return a / b

end

print(pcall(safediv, 10, 2)) -- true 5.0

print(pcall(safediv, 1, 0)) -- false "division by zero"

"close": `-- To-be-closed variables (Lua 5.4+): a local marked <close> runs its value's

-- __close metamethod the moment it leaves scope -- on normal exit, return,

-- break, goto, or an error. Think RAII: open a resource, and it's released

-- deterministically however the block ends.

-- A tiny "resource" whose __close just logs that it was released.

local function resource(name)

print("open " .. name)

return setmetatable({ name = name }, {

__close = function(self) print("close " .. self.name) end,

})

end

print("1) released at end of scope, in reverse order:")

local a <close> = resource("a")

local b <close> = resource("b")

print(" ...using a and b...")

end

print("\\n2) released even when an error unwinds the block:")

print(" pcall ->", pcall(function()

local r <close> = resource("r")

error("boom")

end))

print("\\n3) a generic-for's iterator can carry a closing value,")

print(" released when the loop ends (here: after a break):")

local function lines(n)

local i = 0

local iter = function() i = i + 1; if i <= n then return "line " .. i end end

return iter, nil, nil, resource("file")

end

for text in lines(99) do

print(" " .. text)

if text == "line 2" then break end

end

"iter": `-- A "stateful closure as iterator" — the simplest form of a generic-for

-- iterator. numberGenerator returns a closure that captures \`start\` in a

-- mutable upvalue; each call advances it and returns either the next number

-- or nothing (which generic-for interprets as the end).

local function numberGenerator(start, stop)

return function()

start = start + 1

if start <= stop then

return start

end

-- prints 2, 3, 4, 5

for num in numberGenerator(1, 5) do

print(num)

end

-- A second instance has its own captured \`start\` — closures don't share.

local g = numberGenerator(10, 12)

print(g()) -- 11

print(g()) -- 12

print(g()) -- (no values; print emits a blank line — Lua splices call returns)

"stdin": `-- Exercises io.read(); the test pipes two lines of stdin.

local first = io.read()

local second = io.read()

local third = io.read() -- EOF -> nil

print(first)

print(second)

print(third)

"files": `-- Files, in your browser! io.open / io.lines / io.type read and write a

-- virtual filesystem (powered by just-bash) that PERSISTS across Runs.

-- Click Run a few times and watch the visit counter climb.

local counter = "/demo/visits.txt"

-- Read the previous count. io.open returns nil (not an error) when the

-- file is missing, so the very first Run simply starts from zero.

local n = 0

local f = io.open(counter, "r")

if f then

n = tonumber(f:read("a")) or 0

f:close()

end

n = n + 1

-- Write the new count back. "w" truncates; assert turns a failed open

-- into an error carrying the host's message.

local out = assert(io.open(counter, "w"))

out:write(tostring(n))

out:close()

print("You have run this program " .. n .. " time(s).")

-- A second file shows the rest of the API: multi-arg write, io.lines,

-- byte-accurate read + seek, io.type, and os.remove.

local notes = "/demo/notes.txt"

local g = assert(io.open(notes, "w"))

g:write("buy milk\\n")

g:write("write a compiler\\n", "learn Lua\\n") -- :write takes many args

g:close()

print("\\nnotes.txt, line by line:")

for line in io.lines(notes) do

print(" - " .. line)

end

local r = assert(io.open(notes, "r"))

print("\\nfirst 8 bytes:", r:read(8)) -- "buy milk"

r:seek("set", 0) -- rewind to the start

print("after rewind: ", r:read("l")) -- "buy milk" (whole first line)

print("io.type open: ", io.type(r)) -- file

r:close()

print("io.type closed:", io.type(r)) -- closed file

os.remove(notes)

print("\\nremoved notes.txt — visits.txt stays. That's the persistence!")

"forloop": `local list = {"apple", "banana", "cherry"}

for i, v in ipairs(list) do

print(i)

print(v)

end

local sum = 0

for i = 1, 100 do sum = sum + i end

print(sum) -- 5050

"s_hello": `-- the first program in every language (verbatim from lua.org/extras)

io.write("Hello world, from ",_VERSION,"!\\n")

"s_account": `-- A simple example of OOP in Lua (from PiL 1, ch. 16).

-- Adapted for lua2wasm: only the \`global\` declarations have been added; the

-- rest is byte-for-byte the original from lua.org/extras.

global Account = {balance = 0}

function Account:new (o, name)

o = o or {name=name}

setmetatable(o, self)

self.__index = self

return o

end

function Account:deposit (v)

self.balance = self.balance + v

end

function Account:withdraw (v)

if v > self.balance then error("insufficient funds on account "..self.name) end

self.balance = self.balance - v

end

function Account:show (title)

print(title or "", self.name, self.balance)

end

global a = Account:new(nil,"demo")

a:show("after creation")

a:deposit(1000.00)

a:show("after deposit")

a:withdraw(100.00)

a:show("after withdraw")

"s_bisect": `-- Bisection method for solving non-linear equations.

-- Adapted for lua2wasm: globals are explicitly declared up front; everything

-- else is byte-for-byte the original.

global delta = 1e-6

global n

global bisect

global solve

global f

function bisect(f,a,b,fa,fb)

local c=(a+b)/2

io.write(n," c=",c," a=",a," b=",b,"\\n")

if c==a or c==b or math.abs(a-b)<delta then return c,b-a end

n=n+1

local fc=f(c)

if fa*fc<0 then return bisect(f,a,c,fa,fc) else return bisect(f,c,b,fc,fb) end

end

function solve(f,a,b)

n=0

local z,e=bisect(f,a,b,f(a),f(b))

io.write(string.format("after %d steps, root is %.17g with error %.1e, f=%.1e\\n",n,z,e,f(z)))

end

function f(x)

return x*x*x-x-1

end

solve(f,1,2)

"s_globals": `-- Adapted from lua.org/extras' globals.lua. The original walks Lua's \`_G\`

-- and uses table.sort; our compiler doesn't expose either, so this walks a

-- sample table instead and prints keys in insertion order (which our

-- linear-probe hash table happens to preserve).

local seen = {}

local function dump(t, indent)

seen[t] = true

for k, v in pairs(t) do

print(indent .. k)

if type(v) == "table" and not seen[v] then

dump(v, indent .. " ")

end

local sample = {

alpha = 1,

beta = "hi",

nested = {x = 10, y = 20},

gamma = true,

}

dump(sample, "")

"tjdevries": `--[[

Examples from TJ Devries: "Everything You Need To Start Writing Lua"

https://www.youtube.com/watch?v=CuWfgiwI73Q

--]]

-- This is a comment, It starts with two dashes

--[[ This is also

a comment.

But it spans multiple lines!

--]]

local number = 5

local string = "hello, world"

local single = "also works"

local crazy = [[ This

is multie line and literal ]]

local truth, lies = true, false

local nothing = nil

local function hello(name)

print("Hello!", name)

end

local greet = function(name)

-- .. is string concatenation

print("Greetings, " .. name .. "!")

end

local higher_order = function(value)

return function(another)

return value + another

end

local add_one = higher_order(1)

print("add_one(2) -> ", add_one(2))

local list = {

"first",

false,

function()

print("Fourth!")

end,

}

print("Yup, 1-indexed", list[1])

print("Fourth is 4 ... :", list[4]())

local t = {

literal_key = "a string",

["an expression"] = "also works",

[function() end] = true,

}

print("literal_key : ", t.literal_key)

print("an expression : ", t["an expression"])

print("function() end: ", t[function() end]) -- this print nil, but should print nothing

local favorite_accounts = { "teej_dv", "ThePrimeagen", "terminaldotshop" }

for index = 1, #favorite_accounts do

print(index, favorite_accounts[index])

end

for index, value in ipairs(favorite_accounts) do

print(index, value)

end

local reading_scores = { teej_dv = 9.5, ThePrimeagen = "N/A" }

for index = 1, #reading_scores do

print(reading_scores[index])

end

for key, value in pairs(reading_scores) do

print(key, value)

end

local function action(loves_coffee)

if loves_coffee then

print("Check out \`ssh terminal.shop\` - it's cool!")

else

print("Check out \`ssh terminal.shop\` - it's still cool!")

end

-- "falsey": nil, false

action()

action(false)

-- Everything else is "truthy"

action(true)

action(0)

action({})

--[[ these are wonky since we don't support multiple files in this playground

-- foo.lua

local M = {}

M.cool_function = function() end

return M

-- bar.lua

local foo = require('foo')

foo.cool_function()

--]]

local returns_four_values = function()

return 1, 2, 3, 4

end

first, second, last = returns_four_values()

print("first: ", first)

print("second:", second)

print("last:", last)

-- the \`4\` is discarded :'(

local variable_arguments = function(...)

local arguments = { ... }

for i, v in ipairs({ ... }) do

print(i, v)

end

return table.unpack(arguments)

end

print("===================")

print("1:", variable_arguments("hello", "world", "!"))

print("===================")

print("2:", variable_arguments("hello", "world", "!"), "<lost>")

local single_string = function(s)

return s .. " - WOW!"

end

local x = single_string("hi")

local y = single_string("hi")

print(x, y)

local setup = function(opts)

if opts.default == nil then

opts.default = 17

end

print(opts.default, opts.other)

end

setup({ default = 12, other = false })

setup({ other = true })

local MyTable = {}

function MyTable.something(self, ...) end

function MyTable:something(...) end

local vector_mt = {}

vector_mt.__add = function(left, right)

return setmetatable({

left[1] + right[1],

left[2] + right[2],

left[3] + right[3],

}, vector_mt)

end

local v1 = setmetatable({ 3, 1, 5 }, vector_mt)

local v2 = setmetatable({ -3, 2, 2 }, vector_mt)

local v3 = v1 + v2

print(v3[1], v3[2], v3[3])

print(v3 + v3)

local fib_mt = {

__index = function(self, key)

if key < 2 then return 1 end

-- Update the table, to save the intermediate results

self[key] = self[key - 2] + self[key - 1]

-- Return the result

return self[key]

end

}

local fib = setmetatable({}, fib_mt)

print(fib[5])

print(fib[1000])

};

/* ----- editor ----- */

const editor = new EditorView({

doc: PRESETS.stack,

parent: document.getElementById("editor-host"),

extensions: [

basicSetup,

StreamLanguage.define(luaMode),

catppuccinTheme,

syntaxHighlighting(luaHighlightStyle),

});

document.getElementById("preset").onchange = e => {

const text = PRESETS[e.target.value];

editor.dispatch({ changes: { from: 0, to: editor.state.doc.length, insert: text } });

};

/* ----- output helpers ----- */

const out = document.getElementById("out");

const status = document.getElementById("status");

function clearOut() { out.textContent = ""; }

function logLine(s, cls) {

const node = cls ? document.createElement("span") : document.createTextNode(s + "\n");

if (cls) { node.className = cls; node.textContent = s + "\n"; }

out.appendChild(node);

}

/* ----- lua2wasm compiler (in-browser) ----- */

/* The compiler is a freestanding wasm module built with plain clang (no

* Emscripten); lua2wasm-wasm.mjs is the host glue. It needs only env.abort /

* env.log imports, which the glue supplies. */

status.textContent = "loading compiler…";

const compiler = await loadCompiler(

await (await fetch("../build-wasm/lua2wasm.wasm")).arrayBuffer(),

(line) => logLine(line, "err"),

);

/* Tree-shaking is automatic for programs that don't touch _G/_ENV/load/require,

* so a plain compile already prunes everything it safely can. compiler.compile

* throws on a lex/parse/codegen error; the rest of the UI expects the

* "ERROR(...)" text back, so surface the message (it carries that prefix). */

function luaToWat(source) {

try { return compiler.compile(source); }

catch (e) { return e.message; }

}

/* The $names of functions/globals DCE proves dead in this WAT, as a Set.

* Returns an empty Set if the analysis fails (caller just skips dimming). */

function dceDeadNames(wat) {

return new Set(compiler.deadNames(wat) || []);

}

/* ----- wat -> wasm (built-in assembler, no Binaryen) ----- */

function watToWasm(wat) {

return compiler.assemble(wat); /* throws with the assembler message on failure */

}

/* ----- runtime host ----- */

let curInstance;

const helpers = makeHelpers({ getInstance: () => curInstance, formatFloat, cFormatG, cFormatF, cFormatE });

const { luaToString, formatSpec, parseLuaNumber, osDate, osGetenv, objId } = helpers;

/* Lua's os.clock spec asks for "an approximation of CPU time"; in the

* browser the closest cheap monotonic reading is performance.now() since

* the page loaded. We subtract this baseline at every call. */

const clockEpochMs = performance.now();

/* Virtual filesystem backing io.open / io.lines / os.remove etc. We use

* just-bash's pure in-memory FS, created once and reused across Run

* clicks so a file written in one run is readable in the next (it resets

* on page reload). Its API is async, so the fs host imports below bridge

* through JSPI exactly like io.read does. */

const vfs = new InMemoryFs();

const dirOf = (p) => { const i = p.lastIndexOf("/"); return i <= 0 ? "/" : p.slice(0, i); };

/* ----- the run pipeline ----- */

async function run() {

clearOut();

const t0 = performance.now();

const src = editor.state.doc.toString();

let wat;

try {

wat = luaToWat(src);

} catch (e) { logLine("ERROR (compile): " + e, "err"); return; }

if (wat.startsWith("ERROR")) { logLine(wat, "err"); return; }

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