b0939f6626
* Remove explicit `S` type parameters This commit removes the explicit `S` type parameter on `Func::typed` and `Instance::get_typed_func`. Historical versions of Rust required that this be a type parameter but recent rustcs support a mixture of explicit type parameters and `impl Trait`. This removes, at callsites, a superfluous `, _` argument which otherwise never needs specification. * Fix mdbook examples
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1.4 KiB
WebAssembly Text Format (*.wat)
While not necessarily a full-blown language you might be curious how Wasmtime
interacts with the *.wat text format! The wasmtime CLI and Rust
embedding API both support the *.wat text format by default.
"Hello, World!" is pretty nontrivial in the *.wat format since it's
assembly-like and not really intended to be a primary programming language. That
being said we can create a simple add function to call it!
For example if you have a file add.wat like so:
(module
(func (export "add") (param i32 i32) (result i32)
local.get 0
local.get 1
i32.add))
Then you can execute this on the CLI with:
$ wasmtime add.wat --invoke add 1 2
warning: ...
warning: ...
3
And we can see that we're already adding numbers!
You can also see how this works in the Rust API like so:
# extern crate wasmtime;
# extern crate anyhow;
use wasmtime::*;
# fn main() -> anyhow::Result<()> {
let mut store = Store::<()>::default();
let wat = r#"
(module
(func (export "add") (param i32 i32) (result i32)
local.get 0
local.get 1
i32.add))
"#;
let module = Module::new(store.engine(), wat)?;
let instance = Instance::new(&mut store, &module, &[])?;
let add = instance.get_typed_func::<(i32, i32), i32>(&mut store, "add")?;
println!("1 + 2 = {}", add.call(&mut store, (1, 2))?);
# Ok(())
# }