19 lines
400 B
Rust
19 lines
400 B
Rust
fn fix_help<A, ~B>(f: fn(fn(A) -> B, A) -> B, x: A) -> B {
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ret f(bind fix_help(f, _), x);
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}
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fn fix<A, ~B>(f: fn(fn(A) -> B, A) -> B) -> fn(A) -> B {
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ret bind fix_help(f, _);
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}
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fn fact_(f: fn(int) -> int, n: int) -> int {
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// fun fact 0 = 1
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ret if n == 0 { 1 } else { n * f(n - 1) };
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}
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fn main() {
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let fact = fix(fact_);
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assert (fact(5) == 120);
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assert (fact(2) == 2);
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}
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