github.com/wasilibs/wazerox@v0.0.0-20240124024944-4923be63ab5f/imports/README.md (about)

     1  ## wazero imports
     2  
     3  Packages in this directory implement the *host* imports needed for specific
     4  languages or shared compiler toolchains.
     5  
     6  * [AssemblyScript](assemblyscript) e.g. `asc X.ts --debug -b none -o X.wasm`
     7  * [Emscripten](emscripten) e.g. `em++ ... -s STANDALONE_WASM -o X.wasm X.cc`
     8  * [WASI](wasi_snapshot_preview1) e.g. `tinygo build -o X.wasm -target=wasi X.go`
     9  
    10  Note: You may not see a language listed here because it either works without
    11  host imports, or it uses WASI. Refer to https://wazero.io/languages/ for more.
    12  
    13  Please [open an issue](https://github.com/tetratelabs/wazero/issues/new) if you
    14  would like to see support for another compiled language or toolchain.
    15  
    16  ## Overview
    17  
    18  WebAssembly has a virtual machine architecture where the *host* is the process
    19  embedding wazero and the *guest* is a program compiled into the WebAssembly
    20  Binary Format, also known as Wasm (`%.wasm`).
    21  
    22  The only features that work by default are computational in nature, and the
    23  only way to communicate is via functions, memory or global variables.
    24  
    25  When a compiler targets Wasm, it often needs to import functions from the host
    26  to satisfy system calls needed for functionality like printing to the console,
    27  getting the time, or generating random values. The technical term for this
    28  bridge is Application Binary Interface (ABI), but we'll call them simply host
    29  imports.
    30  
    31  Packages in this directory are sometimes well re-used, such as the case in
    32  [WASI](https://wazero.io/specs/#wasi). For example, Rust, TinyGo, and Zig can
    33  all target WebAssembly in a way that imports the same "wasi_snapshot_preview1"
    34  module in the compiled `%.wasm` file. To support any of these, wazero users can
    35  invoke `wasi_snapshot_preview1.Instantiate` on their `wazero.Runtime`.
    36  
    37  Other times, host imports are either completely compiler-specific, such as the
    38  case with `GOOS=js GOARCH=wasm`, or coexist alongside WASI, such as the case
    39  with Emscripten.