如何在WASM WAT中导入WASI并写一个简单的控制台日志 function

Question

I want to understand the WebAssembly text format for educational purposes and for writing a POC compiler that compiles straight to WASM.

I want to understand how to properly import the necessary WASI functions to create a console log function.

I'd love to see an example written in somewhat readable WAT of a module that imports WASI and implements a simple console log/printf/echo function that can run outside the browser.

eg,

(module
  (func $wasi_snapshot_preview1.fd_close (;0;) (import "wasi_snapshot_preview1" "fd_close") (param i32) (result i32))
  (func $wasi_snapshot_preview1.fd_seek (;1;) (import "wasi_snapshot_preview1" "fd_seek") (param i32 i64 i32 i32) (result i32))
  (func $wasi_snapshot_preview1.fd_write (;2;) (import "wasi_snapshot_preview1" "fd_write") (param i32 i32 i32 i32) (result i32))
  (func $wasi_snapshot_preview1.proc_exit (;3;) (import "wasi_snapshot_preview1" "proc_exit") (param i32))
  (data (; ... ;) )
  (memory (; ... ;) )
  (func $log (; ... ;))
)

Answer 1

This code imports the log function from JS and uses it to print a number:

(module
  (func $log (import "imports" "log") (param i32))
  (func (export "logNumber")
    i32.const 13
    call $log)
)