38 lines
793 B
Rust
38 lines
793 B
Rust
iface to_str {
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fn to_str() -> str;
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}
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impl of to_str for int {
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fn to_str() -> str { int::str(self) }
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}
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impl of to_str for str {
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fn to_str() -> str { self }
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}
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impl of to_str for () {
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fn to_str() -> str { "()" }
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}
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iface map<T> {
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fn map<U>(f: fn(T) -> U) -> ~[U];
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}
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impl <T> of map<T> for ~[T] {
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fn map<U>(f: fn(T) -> U) -> ~[U] {
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let mut r = ~[];
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for self.each {|x| r += ~[f(x)]; }
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r
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}
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}
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fn foo<U, T: map<U>>(x: T) -> ~[str] {
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x.map({|_e| "hi" })
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}
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fn bar<U: to_str, T: map<U>>(x: T) -> ~[str] {
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x.map({|_e| _e.to_str() })
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}
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fn main() {
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assert foo(~[1]) == ~["hi"];
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assert bar::<int, ~[int]>(~[4, 5]) == ~["4", "5"];
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assert bar::<str, ~[str]>(~["x", "y"]) == ~["x", "y"];
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assert bar::<(), ~[()]>(~[()]) == ~["()"];
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}
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