WebAssembly

A ghūl program can be compiled to WebAssembly as well as to .NET. The compiler writes a WasmGC module and a small JavaScript loader beside it, and the program runs under Node.js 22 or newer. The same source builds for either target.

work in progress

The WebAssembly target is new and doesn't yet compile the whole language. Small programs work today; the WebAssembly epic lists what is supported and what is still to come.

installing

A WebAssembly build is driven by the ghul command, the ghul.cli .NET tool, which needs the .NET 10 SDK to install and run. Install it, then bring its compiler up to the latest release:

dotnet tool install -g ghul.cli
ghul install-compiler

ghul builds with the newest compiler it has installed. Each compiler release adds to what the WebAssembly target compiles, so run ghul install-compiler again to update. Running the result needs Node.js 22 or newer.

hello world

A WebAssembly program is a project: a directory holding a ghul-project.json manifest that names the project, its targets and its sources. ghul new creates one, here for both targets:

ghul new hello --target dotnet,wasm
cd hello

--target takes dotnet, wasm or dotnet,wasm, and is dotnet when it is left out. The new directory holds the manifest:

{
    "name": "hello",
    "kind": "program",
    "targets": ["dotnet", "wasm"],
    "sources": ["src/**/*.ghul"]
}

a .gitignore for the build output in out/, and the program, as src/main.ghul:

use IO.Std.write_line

entry() is
    write_line("hello")
si

ghul run builds the project into out/<target>/ and runs it. The manifest lists two targets, so name the one to run:

ghul run --target wasm      # runs out/wasm/hello.mjs under Node.js
ghul run --target dotnet    # runs out/dotnet/hello.exe with dotnet

The first build installs the compiler if there isn't one, and fetches the libraries a WebAssembly build compiles in. Later builds reuse them. A project's sources don't get any implicit imports: each file uses what it calls, or starts with use default for write_line, the pipes and the collections.

ghul build builds without running. The ghul-cli README covers the manifest in full.

the same program on .NET

The program above is ordinary ghūl, and the dotnet target builds it into an ordinary .NET executable. On WebAssembly there is no .NET base class library, so the members of the built-in types and the rest of Ghul come from libraries compiled into the module from source: ghul-core and ghul-runtime. A program that calls .NET APIs directly builds only for the dotnet target.