45 lines
980 B
Rust
45 lines
980 B
Rust
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#![feature(slice_patterns)]
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use std::fmt::Debug;
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fn foldl<T, U, F>(values: &[T],
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initial: U,
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mut function: F)
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-> U where
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U: Clone+Debug, T:Debug,
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F: FnMut(U, &T) -> U,
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{ match values {
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&[ref head, ref tail..] =>
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foldl(tail, function(initial, head), function),
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&[] => {
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let res = initial.clone(); res
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}
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}
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}
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fn foldr<T, U, F>(values: &[T],
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initial: U,
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mut function: F)
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-> U where
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U: Clone,
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F: FnMut(&T, U) -> U,
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{
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match values {
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&[ref head.., ref tail] =>
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foldr(head, function(tail, initial), function),
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&[] => {
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let res = initial.clone(); res
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}
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}
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}
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pub fn main() {
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let x = &[1, 2, 3, 4, 5];
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let product = foldl(x, 1, |a, b| a * *b);
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assert_eq!(product, 120);
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let sum = foldr(x, 0, |a, b| *a + b);
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assert_eq!(sum, 15);
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}
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