44 lines
1.3 KiB
Rust
44 lines
1.3 KiB
Rust
// Copyright 2014 The Rust Project Developers. See the COPYRIGHT
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// file at the top-level directory of this distribution and at
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// http://rust-lang.org/COPYRIGHT.
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//
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// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
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// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
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// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
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// option. This file may not be copied, modified, or distributed
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// except according to those terms.
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#![feature(advanced_slice_patterns)]
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fn foldl<T,U:Clone>(values: &[T],
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initial: U,
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function: |partial: U, element: &T| -> U)
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-> U {
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match values {
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[ref head, tail..] =>
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foldl(tail, function(initial, head), function),
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[] => initial.clone()
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}
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}
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fn foldr<T,U:Clone>(values: &[T],
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initial: U,
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function: |element: &T, partial: U| -> U)
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-> U {
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match values {
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[head.., ref tail] =>
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foldr(head, function(tail, initial), function),
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[] => initial.clone()
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}
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}
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pub fn main() {
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let x = &[1i, 2, 3, 4, 5];
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let product = foldl(x, 1i, |a, b| a * *b);
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assert_eq!(product, 120);
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let sum = foldr(x, 0i, |a, b| *a + b);
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assert_eq!(sum, 15);
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}
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