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-rw-r--r--src/test/ui/run-pass/impl-trait/example-st.rs38
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
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+++ 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));
+}