ParseError.rs

use std::str::FromStr;

struct ParseError<'a, E> {
	error: E,
	source: &'a str,
}

fn parse<'a, T: FromStr>(s: &'a str) -> Result<T, ParseError<'a, T::Err>> {
	s.parse().map_err(|e| ParseError { error: e, source: s })
}

fn main() {
	let a: Result<i32, _> = parse("asdf");

	match a {
		Err(e) => println!("Couldn't parse {:?}: {}", e.source, e.error),
		Ok(i) => println!("Parsed: {}", i),
	}
}