tylar

Type-Level Arithmetic in Rust.

Supports addition, subtraction, multiplication and division of (small-ish*) type-level integers.

Inspired by Björn Buckwalter's numtype library for Haskell. Brought to Rust thanks to multidispatch and associated types.

* Numbers in the range (–50,50) should mostly work, depending on the operations. Typechecking might be rather slow.

Example

// N2 is the type for -2, P5 is +5, Out is the result type
// of the addition; new() creates a new instance (actually a
// no-op, since the types are zero-sized) and into() turns
// the object into an integer value, computed at compile-time
// due to static dispatch.
let result: i32 = <N2 as Add<_,P5>>::Out::new().into();
println!("-2 + 5 = {}", result); // prints `-2 + 5 = 3`

For more, see examples/basics.rs and run cargo run --example basics.

Unfortunately these examples (and therefore also cargo test) do not work with Rust 1.0, but tylar itself is compatible and usable with Rust 1.0.

License

Licensed under either of

• Apache License, Version 2.0, (LICENSE-APACHE or http://www.apache.org/licenses/LICENSE-2.0)
• MIT license (LICENSE-MIT or http://opensource.org/licenses/MIT)

at your option.

Contribution

Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in the work by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms or conditions.