The module shape in WebAssembly

The smallest WebAssembly text: one module, one exported function.

;; Everything lives in one s-expression: a module of declarations.
(module
  ;; Export a function under the name the host will call.
  (func (export "answer") (result i32)
    i32.const 42))

How it works

1. Everything is an s-expression; (module ...) wraps the whole program.
2. (func (export "answer") ...) names the function for the host.
3. (result i32) types the return; i32.const 42 pushes it.

Keywords and builtins used here

• export
• func
• i32
• module
• result

The run, in numbers

Lines

5

Characters to type

182

Tokens

20

Three-star pace

70 tpm

At the three-star pace of 70 tokens a minute, this run takes about 17 seconds.

Type this snippet

Step 1 of 3 in Modules, step 1 of 28 in Language basics.

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