diff options
| -rw-r--r-- | src/libcollections/list.rs | 43 |
1 files changed, 10 insertions, 33 deletions
diff --git a/src/libcollections/list.rs b/src/libcollections/list.rs index d4685f37a39..ce6084923f9 100644 --- a/src/libcollections/list.rs +++ b/src/libcollections/list.rs @@ -54,25 +54,6 @@ impl<T> List<T> { } /** - * Left fold - * - * Applies `f` to `u` and the first element in the list, then applies `f` to - * the result of the previous call and the second element, and so on, - * returning the accumulated result. - * - * # Arguments - * - * * list - The list to fold - * * z - The initial value - * * f - The function to apply - */ -pub fn foldl<T:Clone,U>(z: T, list: @List<U>, f: |&T, &U| -> T) -> T { - let mut accum: T = z; - iter(list, |element| accum = f(&accum, element)); - accum -} - -/** * Search for an element that matches a given predicate * * Apply function `f` to each element of `list`, starting from the first. @@ -258,21 +239,17 @@ mod tests { } #[test] - fn test_foldl() { - fn add(a: &uint, b: &int) -> uint { return *a + (*b as uint); } - let list = @List::from_vec([0, 1, 2, 3, 4]); - let empty = @list::Nil::<int>; - assert_eq!(list::foldl(0u, list, add), 10u); - assert_eq!(list::foldl(0u, empty, add), 0u); - } + fn test_fold() { + fn add_(a: uint, b: &uint) -> uint { a + *b } + fn subtract_(a: uint, b: &uint) -> uint { a - *b } - #[test] - fn test_foldl2() { - fn sub(a: &int, b: &int) -> int { - *a - *b - } - let list = @List::from_vec([1, 2, 3, 4]); - assert_eq!(list::foldl(0, list, sub), -10); + let empty = Nil::<uint>; + assert_eq!(empty.iter().fold(0u, add_), 0u); + assert_eq!(empty.iter().fold(10u, subtract_), 10u); + + let list = List::from_vec([0u, 1u, 2u, 3u, 4u]); + assert_eq!(list.iter().fold(0u, add_), 10u); + assert_eq!(list.iter().fold(10u, subtract_), 0u); } #[test] |