33 lines
1.2 KiB
Rust
33 lines
1.2 KiB
Rust
// Copyright 2012-2015 The Rust Project Developers. See the COPYRIGHT
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// file at the top-level directory of this distribution and at
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// http://rust-lang.org/COPYRIGHT.
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//
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// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
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// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
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// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
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// option. This file may not be copied, modified, or distributed
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// except according to those terms.
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enum Nil {NilValue}
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struct Cons<T> {head:isize, tail:T}
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trait Dot {fn dot(&self, other:Self) -> isize;}
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impl Dot for Nil {
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fn dot(&self, _:Nil) -> isize {0}
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}
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impl<T:Dot> Dot for Cons<T> {
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fn dot(&self, other:Cons<T>) -> isize {
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self.head * other.head + self.tail.dot(other.tail)
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}
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}
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fn test<T:Dot> (n:isize, i:isize, first:T, second:T) ->isize { //~ ERROR recursion limit
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match n { 0 => {first.dot(second)}
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// FIXME(#4287) Error message should be here. It should be
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// a type error to instantiate `test` at a type other than T.
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_ => {test (n-1, i+1, Cons {head:2*i+1, tail:first}, Cons{head:i*i, tail:second})}
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}
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}
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pub fn main() {
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let n = test(1, 0, Nil::NilValue, Nil::NilValue);
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println!("{}", n);
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}
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