Examples

The repo's examples/ directory has runnable .fv files plus a walkthrough that uses the wasmtime CLI — no Rust host code required.

Install the toolchain

# formawasm CLI
cargo install formawasm

# wasmtime CLI
curl https://wasmtime.dev/install.sh -sSf | bash
# Or: brew install wasmtime

Compile and run

The repo's numbered .fv files each declare one or more pub fn exports plus a pub fn run_checks() that asserts the expected outputs. Compile any of them with the CLI:

formawasm examples/02_generics_pair_result.fv
wasmtime run --invoke 'pair-sum()' examples/02_generics_pair_result.wasm
# 3

Examples like 12_numeric_primitives.fv carry several primitive-typed exports in one component:

formawasm examples/12_numeric_primitives.fv
wasmtime run --invoke 'i32-add(7, 35)'  examples/12_numeric_primitives.wasm   # 42
wasmtime run --invoke 'i64-mul(6, 7)'   examples/12_numeric_primitives.wasm   # 42

To exercise the embedded assert(...) calls in each example's run-checks export, run the test harness — it wires assert to a host function that traps on false, so passing means every embedded assertion held:

cargo test --test examples

Limits of wasmtime --invoke

--invoke is built for primitive parameter and return types. Components whose signatures involve string, list<T>, record, or variant need a richer host:

• A Rust wrapper built with wasmtime::component::bindgen! — see Hosting a Component.
• jco — JavaScript host bindings, runs in Node.js or the browser.
• wasmtime serve — HTTP-world components without per-feature glue.

The fully-walked-through commands and notes live in examples/README.md in the repo.