// run-pass #![allow(non_camel_case_types)] trait to_str { fn to_string_(&self) -> String; } impl to_str for isize { fn to_string_(&self) -> String { self.to_string() } } impl to_str for String { fn to_string_(&self) -> String { self.clone() } } impl to_str for () { fn to_string_(&self) -> String { "()".to_string() } } trait map { fn map(&self, f: F) -> Vec where F: FnMut(&T) -> U; } impl map for Vec { fn map(&self, mut f: F) -> Vec where F: FnMut(&T) -> U { let mut r = Vec::new(); for i in self { r.push(f(i)); } r } } fn foo>(x: T) -> Vec { x.map(|_e| "hi".to_string() ) } fn bar>(x: T) -> Vec { x.map(|_e| _e.to_string_() ) } pub fn main() { assert_eq!(foo(vec![1]), ["hi".to_string()]); assert_eq!(bar:: >(vec![4, 5]), ["4".to_string(), "5".to_string()]); assert_eq!(bar:: >(vec!["x".to_string(), "y".to_string()]), ["x".to_string(), "y".to_string()]); assert_eq!(bar::<(), Vec<()>>(vec![()]), ["()".to_string()]); }