WebAssembly code is typically written and read in two formats: wasm which is a binary format and the WebAssembly Text (WAT) format. WAT, similar to assembly language for conventional machines, offers a human-readable version of WebAssembly binary code.

For example, if we have the following C++ code:

1#include <iostream>
2using namespace std;
3int main() {
4  cout << "Welcome to WebAssembly!";
5  return 0;
6}

This could be compiled down into a WAT representation that looks something like this:

1(module
2  (import "env" "putchar" (func $putchar (param i32)))
3  (func $main (export "main") (param) (result i32)
4    i32.const 0
5  )
6
7  (func $writeString (param i32)
8    get_local 0
9    call $putchar
10    drop
11  )
12)

The key takeaway here is that WAT is a representation of the binary code that can be written and read by humans. However, it's not as convenient to write as higher-level languages. WAT is more like a tool that aids in understanding, debugging, and optimizing WebAssembly applications.

Usually, we use WAT when we want a clear view of what our higher-level language code (like C++ or Rust) compiles down into, it helps to understand the instructions and structure of the code.

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#include <iostream>

using namespace std;

int main() {

  cout << "Welcome to WebAssembly!";

  return 0;

}