Crate rsmonad_macros

Provides the monad! {...} macro, which parses (1) a data structure definition, (2) a function bind, and (3) a function consume, and implements the most idiomatic macro available as Rust continues to evolve.

Use

// use rsmonad::prelude::*; // <-- In your code, use this; here, though, we redefine a simpler `Maybe`, so we can't import everything
use rsmonad::prelude::{Monad, monad};

monad! {
    /// Encodes the possibility of failure.
    enum ExampleMaybe<A> {
        EgNothing,
        EgJust(A),
    }

    fn bind(self, f) {
        match self {
            EgNothing => EgNothing,
            EgJust(b) => f(b),
        }
    }

    fn consume(a) {
        EgJust(a)
    }
}

fn could_overflow(x: u8) -> ExampleMaybe<u8> {
    x.checked_add(1).map_or(EgNothing, EgJust)
}

assert_eq!(
    EgNothing >> could_overflow,
    EgNothing
);
assert_eq!(
    EgJust(1) >> could_overflow,
    EgJust(2)
);
assert_eq!(
    EgJust(255) >> could_overflow,
    EgNothing
);

Macros

• monad
  Write the boilerplate for a monad given the minimal definition.