Playground

The Nolang Playground is an online environment where you can edit, compile, and run Nolang programs directly in the browser. It compiles the Nolang compiler (no.wasm) and language server (lsp.wasm) to WebAssembly and executes user code inside the browser sandbox via WASI — no local toolchain installation required.

Go now: /playground

Usage

The Playground page is split into two panes:

• Left Editor: A code editor based on CodeMirror 6, with Nolang syntax highlighting, auto-indentation, and history.
• Right Output / stderr / Diagnostics: Execution results, standard error output, and diagnostic messages.

Toolbar

Button	Function
▶ Run	Compile the current code to WASM and execute via WASI; stdout shown in the right Output pane.
Format	Call no fmt through the LSP to format the current code.
Examples	Load a program from the built-in example list, replacing the editor content.

Examples

The Examples dropdown comes with 6 common presets:

• Hello World — the simplest print and string concatenation
• Fibonacci — iterative and recursive Fibonacci
• Variables & Functions — variable declarations, types, function definitions, multi-return values
• Structs & Methods — struct definition, instantiation, methods
• Match Expression — x: { ... } pattern matching
• math/rand — generating random numbers with the rand standard library

Selecting an example clears the current Output, stderr, and Diagnostics, then replaces the editor with that example's content.

Diagnostics

When the LSP detects syntax or type errors, they appear in the Diagnostics area at the bottom-right. Clicking any diagnostic item navigates to the corresponding line and column.

Limitations

Because the Playground runs inside a browser WASM sandbox, some Nolang features are unavailable:

No FFI

The browser cannot link native C libraries, so #{c}, #{cpp}, #{rust} FFI declarations cannot be used in the Playground. Code that involves FFI (such as sqlite or mysql drivers) cannot execute.

No fork / exec / pipe

WASI preview1 does not provide process management APIs, so the process standard library (process.start, process.wait, etc.) is not available in the Playground.

Network sockets unavailable

WASI preview1 does not provide socket APIs, so the following standard libraries are unavailable in the Playground:

• net (TCP listener / conn)
• http / http2 / http3 (HTTP client)
• ws (WebSocket)
• tls (TLS connection)
• quic, sse, dns

Virtual filesystem

WASI preview1 only provides stdin / stdout / stderr file descriptors — there is no real filesystem. Therefore fs, path, os.get-env, os.set-env and other file/environment-related standard libraries may not work as expected in the Playground.

Memory limit

Browser WASM is typically constrained by a 32-bit address space; the usable memory ceiling is approximately 2 GB – 4 GB (depending on the browser and OS). Programs requiring large memory (such as deep recursion or large arrays) may fail due to out-of-memory.

Browser Compatibility

The Playground requires a modern browser with WebAssembly support. The following versions or later are recommended:

Browser	Minimum Version
Chrome	100+
Firefox	100+
Safari	16+
Edge	100+

If the browser does not support WebAssembly or has JavaScript disabled, the Playground will be unable to load the editor or execute code.