34 lines
710 B
Rust
34 lines
710 B
Rust
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fn foldl<T, U: Copy>(
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values: &[T],
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initial: U,
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function: &fn(partial: U, element: &T) -> U
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) -> U {
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match values {
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[head, ..tail] =>
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foldl(tail, function(initial, &head), function),
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[] => copy initial
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}
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}
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fn foldr<T, U: Copy>(
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values: &[T],
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initial: U,
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function: &fn(element: &T, partial: U) -> U
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) -> U {
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match values {
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[..head, tail] =>
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foldr(head, function(&tail, initial), function),
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[] => copy initial
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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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fail_unless!(product == 120);
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let sum = foldr(x, 0, |a, b| *a + b);
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fail_unless!(sum == 15);
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}
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