diff options
Diffstat (limited to 'src/test/ui/unboxed-closures/unboxed-closures-infer-recursive-fn.rs')
-rw-r--r-- | src/test/ui/unboxed-closures/unboxed-closures-infer-recursive-fn.rs | 45 |
1 files changed, 0 insertions, 45 deletions
diff --git a/src/test/ui/unboxed-closures/unboxed-closures-infer-recursive-fn.rs b/src/test/ui/unboxed-closures/unboxed-closures-infer-recursive-fn.rs deleted file mode 100644 index a0fbbafe2..000000000 --- a/src/test/ui/unboxed-closures/unboxed-closures-infer-recursive-fn.rs +++ /dev/null @@ -1,45 +0,0 @@ -// run-pass -#![feature(fn_traits, unboxed_closures)] - -use std::marker::PhantomData; - -// Test that we are able to infer a suitable kind for a "recursive" -// closure. As far as I can tell, coding up a recursive closure -// requires the good ol' [Y Combinator]. -// -// [Y Combinator]: https://en.wikipedia.org/wiki/Fixed-point_combinator#Y_combinator - -struct YCombinator<F,A,R> { - func: F, - marker: PhantomData<(A,R)>, -} - -impl<F,A,R> YCombinator<F,A,R> { - fn new(f: F) -> YCombinator<F,A,R> { - YCombinator { func: f, marker: PhantomData } - } -} - -impl<A,R,F : Fn(&dyn Fn(A) -> R, A) -> R> Fn<(A,)> for YCombinator<F,A,R> { - extern "rust-call" fn call(&self, (arg,): (A,)) -> R { - (self.func)(self, arg) - } -} - -impl<A,R,F : Fn(&dyn Fn(A) -> R, A) -> R> FnMut<(A,)> for YCombinator<F,A,R> { - extern "rust-call" fn call_mut(&mut self, args: (A,)) -> R { self.call(args) } -} - -impl<A,R,F : Fn(&dyn Fn(A) -> R, A) -> R> FnOnce<(A,)> for YCombinator<F,A,R> { - type Output = R; - extern "rust-call" fn call_once(self, args: (A,)) -> R { self.call(args) } -} - -fn main() { - let factorial = |recur: &dyn Fn(u32) -> u32, arg: u32| -> u32 { - if arg == 0 {1} else {arg * recur(arg-1)} - }; - let factorial: YCombinator<_,u32,u32> = YCombinator::new(factorial); - let r = factorial(10); - assert_eq!(3628800, r); -} |