rust/src/test/run-pass/vec-matching-fold.rs
Niko Matsakis 9e3d0b002a librustc: Remove the fallback to int from typechecking.
This breaks a fair amount of code. The typical patterns are:

* `for _ in range(0, 10)`: change to `for _ in range(0u, 10)`;

* `println!("{}", 3)`: change to `println!("{}", 3i)`;

* `[1, 2, 3].len()`: change to `[1i, 2, 3].len()`.

RFC #30. Closes #6023.

[breaking-change]
2014-06-24 17:18:48 -07:00

42 lines
1.2 KiB
Rust

// 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.
fn foldl<T,U:Clone>(values: &[T],
initial: U,
function: |partial: U, element: &T| -> U)
-> U {
match values {
[ref head, ..tail] =>
foldl(tail, function(initial, head), function),
[] => initial.clone()
}
}
fn foldr<T,U:Clone>(values: &[T],
initial: U,
function: |element: &T, partial: U| -> U)
-> U {
match values {
[..head, ref tail] =>
foldr(head, function(tail, initial), function),
[] => initial.clone()
}
}
pub fn main() {
let x = [1i, 2, 3, 4, 5];
let product = foldl(x, 1i, |a, b| a * *b);
assert_eq!(product, 120);
let sum = foldr(x, 0i, |a, b| *a + b);
assert_eq!(sum, 15);
}