1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
|
//@ run-pass
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);
}
|
