diff options
Diffstat (limited to 'src/test/ui/run-pass/impl-trait/example-st.rs')
| -rw-r--r-- | src/test/ui/run-pass/impl-trait/example-st.rs | 38 | 
1 files changed, 38 insertions, 0 deletions
| diff --git a/src/test/ui/run-pass/impl-trait/example-st.rs b/src/test/ui/run-pass/impl-trait/example-st.rs new file mode 100644 index 00000000000..a06bde7f532 --- /dev/null +++ b/src/test/ui/run-pass/impl-trait/example-st.rs @@ -0,0 +1,38 @@ +// Copyright 2016 The Rust Project Developers. See the COPYRIGHT +// file at the top-level directory of this distribution and at +// http://rust-lang.org/COPYRIGHT. +// +// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or +// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license +// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your +// option. This file may not be copied, modified, or distributed +// except according to those terms. + +struct State; +type Error = (); + +trait Bind<F> { + type Output; + fn bind(self, f: F) -> Self::Output; +} + +fn bind<T, U, A, B, F>(mut a: A, mut f: F) + -> impl FnMut(&mut State) -> Result<U, Error> +where F: FnMut(T) -> B, + A: FnMut(&mut State) -> Result<T, Error>, + B: FnMut(&mut State) -> Result<U, Error> +{ + move |state | { + let r = a(state)?; + f(r)(state) + } +} + +fn atom<T>(x: T) -> impl FnMut(&mut State) -> Result<T, Error> { + let mut x = Some(x); + move |_| x.take().map_or(Err(()), Ok) +} + +fn main() { + assert_eq!(bind(atom(5), |x| atom(x > 4))(&mut State), Ok(true)); +} | 
