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bytecodealliance / go-modules

WebAssembly, WASI, and Component Model tools for Go
https://go.bytecodealliance.org
Apache License 2.0
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component-model go golang wasi wasm webassembly

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go.bytecodealliance.org

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WebAssembly, WASI, and Component Model tools for Go and TinyGo.

About

Package wit/bindgen contains code to generate Go bindings for Component Model interfaces defined in WIT (WebAssembly Interface Type) files. A goal of this project is to accelerate adoption of the Component Model and development of WASI 0.2+ in Go.

Component Model

Package cm contains helper types and functions used by generated packages, such as option<t>, result<ok, err>, variant, list, and resource. These are intended for use by generated Component Model bindings, where the caller converts to a Go equivalent. It attempts to map WIT semantics to their equivalent in Go where possible.

Note on Memory Safety

Package cm and generated bindings from wit-bindgen-go may have compatibility issues with the Go garbage collector, as they directly represent variant and result types as tagged unions where a pointer shape may be occupied by a non-pointer value. The GC may detect and throw an error if it detects a non-pointer value in an area it expects to see a pointer. This is an area of active development.

wit-bindgen-go

WIT → Go

The wit-bindgen-go tool can generate Go bindings for WIT interfaces and worlds. If wasm-tools is installed and in $PATH, then wit-bindgen-go can load WIT directly.

wit-bindgen-go generate ../wasi-cli/wit

Otherwise, pass the JSON representation of a fully-resolved WIT package:

wit-bindgen-go generate wasi-cli.wit.json

Or pipe via stdin:

wasm-tools component wit -j --all-features ../wasi-cli/wit | wit-bindgen-go generate

JSON → WIT

For debugging purposes, wit-bindgen-go can also convert a JSON representation back into WIT. This is useful for validating that the intermediate representation faithfully represents the original WIT source.

wit-bindgen-go wit example.wit.json

WIT → JSON

Package wit can decode a JSON representation of a fully-resolved WIT file. Serializing WIT into JSON requires wasm-tools v1.210.0 or higher. To convert a WIT file into JSON, run wasm-tools with the -j argument:

wasm-tools component wit -j --all-features example.wit

This will emit JSON on stdout, which can be piped to a file or another program.

wasm-tools component wit -j --all-features example.wit > example.wit.json

License

This project is licensed under the Apache 2.0 license with the LLVM exception. See LICENSE for more details.