1 // Copyright 2012-2014 The Rust Project Developers. See the COPYRIGHT
2 // file at the top-level directory of this distribution and at
3 // http://rust-lang.org/COPYRIGHT.
5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
8 // option. This file may not be copied, modified, or distributed
9 // except according to those terms.
13 // pretty-expanded FIXME #23616
16 fn bind<B, F>(&self, f: F ) -> Vec<B> where F: FnMut(&A) -> Vec<B> ;
19 impl<A> vec_monad<A> for Vec<A> {
20 fn bind<B, F>(&self, mut f: F) -> Vec<B> where F: FnMut(&A) -> Vec<B> {
21 let mut r = Vec::new();
23 r.extend(f(elt).into_iter());
29 trait option_monad<A> {
30 fn bind<B, F>(&self, f: F) -> Option<B> where F: FnOnce(&A) -> Option<B>;
33 impl<A> option_monad<A> for Option<A> {
34 fn bind<B, F>(&self, f: F) -> Option<B> where F: FnOnce(&A) -> Option<B> {
36 Some(ref a) => { f(a) }
42 fn transform(x: Option<int>) -> Option<String> {
43 x.bind(|n| Some(*n + 1) ).bind(|n| Some(n.to_string()) )
47 assert_eq!(transform(Some(10)), Some("11".to_string()));
48 assert_eq!(transform(None), None);
49 assert_eq!((vec!("hi".to_string()))
50 .bind(|x| vec!(x.clone(), format!("{}!", x)) )
51 .bind(|x| vec!(x.clone(), format!("{}?", x)) ),