7a1b7cdf92
Implement Wasmtime's new API as designed by RFC 11. This is quite a large commit which has had lots of discussion externally, so for more information it's best to read the RFC thread and the PR thread.
57 lines
1.4 KiB
Markdown
57 lines
1.4 KiB
Markdown
# WebAssembly Text Format (`*.wat`)
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While not necessarily a full-blown language you might be curious how Wasmtime
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interacts with [the `*.wat` text format][spec]! The `wasmtime` CLI and Rust
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embedding API both support the `*.wat` text format by default.
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"Hello, World!" is pretty nontrivial in the `*.wat` format since it's
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assembly-like and not really intended to be a primary programming language. That
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being said we can create a simple add function to call it!
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For example if you have a file `add.wat` like so:
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```wat
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(module
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(func (export "add") (param i32 i32) (result i32)
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local.get 0
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local.get 1
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i32.add))
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```
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Then you can execute this on the CLI with:
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```sh
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$ wasmtime add.wat --invoke add 1 2
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warning: ...
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warning: ...
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3
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```
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And we can see that we're already adding numbers!
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You can also see how this works in the Rust API like so:
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```rust
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# extern crate wasmtime;
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# extern crate anyhow;
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use wasmtime::*;
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# fn main() -> anyhow::Result<()> {
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let mut store = Store::<()>::default();
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let wat = r#"
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(module
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(func (export "add") (param i32 i32) (result i32)
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local.get 0
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local.get 1
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i32.add))
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"#;
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let module = Module::new(store.engine(), wat)?;
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let instance = Instance::new(&mut store, &module, &[])?;
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let add = instance.get_typed_func::<(i32, i32), i32, _>(&mut store, "add")?;
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println!("1 + 2 = {}", add.call(&mut store, (1, 2))?);
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# Ok(())
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# }
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```
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[spec]: https://webassembly.github.io/spec/core/text/index.html
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