Wasienv Docs • Slack • Twitter

Wasienv is a tool that aims to bring all programming languages to WebAssembly WASI. With wasienv you can compile:

• C/C++ projects to Wasm + WASI (see usage example)
• Swift to Wasm + WASI (see usage example)

So you can run them anywhere (with any Standalone WASI WebAssembly runtime, or in the Browser).

Note: If you aim to use the WebAssembly files in the web directly (using graphics, audio or other tools that are not supported in WASI) then Emscripten is probably a much better choice.

You can install wasienv with:

curl https://raw.githubusercontent.com/wasienv/wasienv/master/install.sh | sh

Note: we also ship wasienv in a Docker image. You can check how to use the Wasienv Docker image here.

If you want to compile a C file to a WebAssembly WASI:

# To compile to a WebAssembly WASI file
# This command will generate:
#  • An executable: ./example
#  • A WebAssembly file: ./example.wasm
wasicc examples/example.c -o example

# If you are using configure
wasiconfigure ./configure

# If you are using cmake (or make)
wasimake cmake .

If you want to compile a C file to plain WebAssembly:

# To compile to a WebAssembly file
# This command will generate:
#  • An executable: ./example
#  • A WebAssembly file: ./example.wasm
wasmcc examples/example.c -o example

When installing wasienv, the following commands will be automatically available:

This is the compiler toolchain. You have two commands available:

For installing a SDK (wasienv install-sdk):

wasienv install-sdk 7

For setting a SDK as the default (wasienv default-sdk):

wasienv default-sdk 7

It's a wrapper on top of clang, with additions for the stubs, sysroot and target. It also detects autoexecutables in the output and wraps to execute them with a WebAssembly WASI runtime via wasirun.

It's a wrapper on top of clang++, with additions for the stubs, sysroot and target. It also detects autoexecutables in the output and wraps to execute them with a WebAssembly WASI runtime via wasirun.

It's a wrapper on top of clang, with additions for preconfiguring the wasm linker, target, etc...

It's a wrapper on top of clang++, with additions for preconfiguring the wasm linker, target, etc...

It's a helper that adds the wasienv environment vars (CC, CXX, RUNLIB, ...) to the following command (./configure).

Example:

wasiconfigure ./configure

It's a helper that adds the wasienv environment vars (CC, CXX, RUNLIB, ...) for the make (make or cmake).

Example:

# With CMake
wasimake cmake .

# With Make
wasimake make

It executes a given WebAssembly file with a standalone WebAssembly runtime.

wasirun myfile.wasm

If you want to compile a Swift file to a WebAssembly WASI, you will need to first install the Wasienv Swift integration:

wasienv install-swift

Once the integration is installed, you can start compiling Swift files to WebAssembly!

It compiles your Swift files into WebAssembly.

wasiswiftc example.swift -o example.wasm

After cloning this repo, ensure dependencies are installed by running:

make install-dev

After that, all the commands will be available on your shell and you should be able to start seeing the changes directly without re-installing wasienv.

After running make install-dev you can run directly:

make test

Emscripten is a great toolchain that let's you compile your C/C++ projects to WebAssembly so you can use them in the web easily.

However, Emscripten has a non-stable ABI (because constant and fast iteration is very useful for their usecase). This makes it a bit challening for standalone-runtimes to continually adapt. Because of that, adopting the WASI ABI is a much easier path for standalone server-side WebAssembly runtimes.

Right now Emscripten is moving towards WASI adoption. However, Emscripten can only emit WASI WebAssembly files for some programs as Emscripten's filesystem layer supports POSIX features not yet present in WASI.

Emscripten has also some tools that are not needed (nor supported) in the case of server-side Standalone WebAssembly runtimes, such as EM_JS and EM_ASM.

Wasienv learns a lot from Emscripten, since they figured out the perfect ergonomics for having C/C++ projects to adopt WebAssembly. Alon, the creator of Emscripten, is without any doubt one of the brilliant minds behind WebAssembly and he inspired us with his work to keep improving the ergonomics of WASI.

WASI-libc is the "frontend ABI" for WASI. By itself, it only provides header files and implementations that make C compilers adopt WASI very easily via the --sysroot flag.

We can see WASI-SDK as the union between WASI-libc and the compiler binaries clang, wasm-ld, ...

Wasienv is using WASI-SDK under the hood to compile to WebAssembly, however it differs from it in two major ways:

1. wasienv is designed to work with multiple SDKs versions
2. wasienv is completely focused on the ergonomics, exposing very simple to use CLI tools so that projects can adopt it easily.

We can think of wasienv as applying the ergonomic ideas from Emscripten to the WASI-SDK