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