25 lines
471 B
Rust
25 lines
471 B
Rust
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// run-pass
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#![feature(try_trait_v2)]
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use std::ops::Try;
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fn monad_unit<T: Try>(x: <T as Try>::Output) -> T {
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T::from_output(x)
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}
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fn monad_bind<T1: Try<Residual = R>, T2: Try<Residual = R>, R>(
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mx: T1,
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f: impl FnOnce(<T1 as Try>::Output) -> T2)
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-> T2 {
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let x = mx?;
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f(x)
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}
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fn main() {
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let mx: Option<i32> = monad_unit(1);
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let my = monad_bind(mx, |x| Some(x + 1));
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let mz = monad_bind(my, |x| Some(-x));
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assert_eq!(mz, Some(-2));
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}
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