rustc/vendor/macro-utils/src/tern_haskell.rs

// MIT License
//
// Copyright (c) 2018 Guillaume Gomez
//
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// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
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// furnished to do so, subject to the following conditions:
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/// You miss Haskell-like ternary conditions? Why not having them in Rust then?
///
/// ```
/// # #[macro_use] extern crate macro_utils;
/// let y = 4;
/// let x = tern_haskell! { if (y & 1 == 0) then { "it's even" } else { "it's odd" } };
///
/// println!("{} is {}", y, x);
/// ```
#[macro_export]
macro_rules! tern_haskell {
    (if ($cond:expr) then { $if_expr:expr } else { $else_expr:expr }) => {
        if $cond {
            $if_expr
        } else {
            $else_expr
        }
    };
}

#[test]
fn tern_haskell() {
    let y = 4;
    let x = tern_haskell! { if (y & 1 == 0) then { "it's even" }  else { "it's odd" } };

    assert_eq!(x, "it's even");
}