WebAssembly · Expert

Lesson 1 · On the house

Validation and the typed stack

How the validator types every instruction, and the polymorphic stack after unreachable.

Lesson 2

Binary format and LEB128

Magic, version, section ids, and variable-length integer encoding.

Lesson 3

Tail calls

return_call and return_call_indirect for constant-stack recursion and interpreters.

Lesson 4

Exception handling with try_table

Tags, throw, try_table catch clauses, and exnref rethrow.

Lesson 5

GC types: structs and arrays

struct.new, struct.get, arrays, subtyping, and ref.cast for managed languages.

Lesson 6

Memory64 and multi-memory

i64 addresses beyond 4 GiB, and several memories in one module.

Lesson 7

Shared memory: wait and notify

Spinlocks with cmpxchg, futex-style wait32, and notify counts.

Lesson 8

The Component Model and WIT

Interfaces in WIT, worlds, canonical ABI lifting, and composing components.

Lesson 9

WASI 0.2 and wasmtime

Preview 2 worlds, capability-based files, and running components from the CLI.

Lesson 10

Sandboxing and engine internals

Bounds checks, guard pages, typed indirect calls, and tiered compilation.