34c282ac2e
While type-checking the AST for a pattern, ISLE was passing in an
`Option<TypeId>` for the expected result type of the pattern. However,
at every call we either passed `Some` type explicitly, or passed the
parent's expected type in a self-recursive call.
Therefore, by induction, `expected_ty` is never `None`. So this PR
unwraps the type everywhere. That in turn shows that a bunch of error
messages were unreachable, so this deletes a bunch of error-handling
code.
In addition, this function returned the type it computed for the
sub-pattern, but that information is already available in the
sub-pattern itself. Not only that but the type should always be equal to
`expected_ty`; when it isn't, we've reported a type error and are just
trying to check for more errors.
Most callers ignored the returned type but in some cases we used it to
try to avoid emitting useless error messages. I've preserved that
behavior for bind-patterns.
For and-patterns, the returned type looked like it was being used, but
because `expected_ty` was never `None`, the fallback of "fill in with
the sub-pattern's type" never fired. So I've deleted that fallback.
Finally, this reverts #4915 (9d99eff6f9)
which was introduced to flatten nested and-patterns, to simplify overlap
checking. However, the visitor trait used by trie_again effectively
flattens and-patterns anyway, so the current representation used for
overlap checking doesn't need this any more.
wasmtime
A standalone runtime for WebAssembly
A Bytecode Alliance project
Guide | Contributing | Website | Chat
Installation
The Wasmtime CLI can be installed on Linux and macOS (locally) with a small install script:
curl https://wasmtime.dev/install.sh -sSf | bash
Windows or otherwise interested users can download installers and binaries directly from the GitHub Releases page.
Example
If you've got the Rust compiler installed then you can take some Rust source code:
fn main() {
println!("Hello, world!");
}
and compile/run it with:
$ rustup target add wasm32-wasi
$ rustc hello.rs --target wasm32-wasi
$ wasmtime hello.wasm
Hello, world!
(Note: make sure you installed Rust using the rustup method in the official
instructions above, and do not have a copy of the Rust toolchain installed on
your system in some other way as well (e.g. the system package manager). Otherwise, the rustup target add...
command may not install the target for the correct copy of Rust.)
Features
-
Fast. Wasmtime is built on the optimizing Cranelift code generator to quickly generate high-quality machine code either at runtime or ahead-of-time. Wasmtime is optimized for efficient instantiation, low-overhead calls between the embedder and wasm, and scalability of concurrent instances.
-
Secure. Wasmtime's development is strongly focused on correctness and security. Building on top of Rust's runtime safety guarantees, each Wasmtime feature goes through careful review and consideration via an RFC process. Once features are designed and implemented, they undergo 24/7 fuzzing donated by Google's OSS Fuzz. As features stabilize they become part of a release, and when things go wrong we have a well-defined security policy in place to quickly mitigate and patch any issues. We follow best practices for defense-in-depth and integrate protections and mitigations for issues like Spectre. Finally, we're working to push the state-of-the-art by collaborating with academic researchers to formally verify critical parts of Wasmtime and Cranelift.
-
Configurable. Wasmtime uses sensible defaults, but can also be configured to provide more fine-grained control over things like CPU and memory consumption. Whether you want to run Wasmtime in a tiny environment or on massive servers with many concurrent instances, we've got you covered.
-
WASI. Wasmtime supports a rich set of APIs for interacting with the host environment through the WASI standard.
-
Standards Compliant. Wasmtime passes the official WebAssembly test suite, implements the official C API of wasm, and implements future proposals to WebAssembly as well. Wasmtime developers are intimately engaged with the WebAssembly standards process all along the way too.
Language Support
You can use Wasmtime from a variety of different languages through embeddings of the implementation.
Languages supported by the Bytecode Alliance:
- Rust - the
wasmtimecrate - C - the
wasm.h,wasi.h, andwasmtime.hheaders, CMake orwasmtimeConan package - C++ - the
wasmtime-cpprepository or usewasmtime-cppConan package - Python - the
wasmtimePyPI package - .NET - the
WasmtimeNuGet package - Go - the
wasmtime-gorepository - Ruby - the
wasmtimegem
Languages supported by the community:
- Elixir - the
wasmexhex package
Documentation
📚 Read the Wasmtime guide here! 📚
The wasmtime guide is the best starting point to learn about what Wasmtime can do for you or help answer your questions about Wasmtime. If you're curious in contributing to Wasmtime, it can also help you do that!
It's Wasmtime.