WAT to WASM Converter

WAT is the S-expression based human-readable text representation of WebAssembly. Every .wasm binary has an equivalent .wat form that can be round-tripped via the wabt toolchain. WAT uses parenthesized expressions like (func $add (param i32 i32) (result i32) ...) to describe modules. It's the primary format for hand-authoring small WASM modules, debugging disassembled binaries, and learning WASM internals.

Install wabt (WebAssembly Binary Toolkit): 'npm install -g wabt' or 'brew install wabt'. Then run: wat2wasm module.wat -o module.wasm. To go the other direction (disassemble): wasm2wat module.wasm -o module.wat. You can also validate without producing output: wat2wasm module.wat --output=-. The online wat.js project lets you compile WAT in the browser via JavaScript.

WebAssembly MVP supports four value types: i32 (32-bit integer), i64 (64-bit integer), f32 (32-bit float), f64 (64-bit float). The post-MVP additions include v128 (128-bit SIMD vector), funcref (function reference), and externref (host object reference). There is no boolean type — conditions use i32 where 0 is false and non-zero is true. Strings are not a native type; they're stored in linear memory as UTF-8 bytes.

WebAssembly uses a stack-based virtual machine. Instructions push values onto and pop values off an implicit stack. For example, 'i32.add' pops two i32 values from the stack and pushes their sum. 'local.get $x' pushes the value of local variable $x. Function parameters and locals are indexed. The WAT text format also supports a folded (S-expression) notation that looks more like a tree: (i32.add (local.get $a) (local.get $b)).

WASM linear memory is a contiguous, byte-addressable buffer (WebAssembly.Memory). It starts at a specified size (in 64KB pages) and can grow with memory.grow. You declare it as (memory 1) for one 64KB page. JavaScript can read/write it via typed arrays on the buffer: new Uint8Array(instance.exports.memory.buffer). The (data ...) instruction initializes memory at module load. Pointers in WASM are just i32 byte offsets into this linear address space.