Shared via Rust Playground

playground.rs

use std::collections::HashMap;
use std::io;
use std::io::prelude::*;
use std::io::BufReader;
use std::fs::File;
use std::error::Error;
use std::mem;
use std::str;

type Something<'a> = HashMap<&'a str, &'a str>;

fn get_lines(filename: &str) -> Result<io::Lines<BufReader<File>>, io::Error> {
	let mut f = try!(File::open(filename));
	Ok(BufReader::new(f).lines())
}

fn get_something<'a>() -> Result<&'a Something<'a>, io::Error> {
	let mut something = Something::new();
	try!(get_lines("gates.txt"))
	    .map(|line| line.unwrap().as_ref())
	    .map(|line| something.insert(line, line));
	Ok(&something)
}
fn main() {
	match get_something() {
		Ok(something) => println!("Values: (yay, {})", something.get("yay").unwrap()),
		Err(e) => println!("Error: {}", e.to_string()),
	}
}

:22:6: 22:15 error: something does not live long enough
:22 Ok(&something)
^~~~~~~~~
:17:64: 23:2 note: reference must be valid for the lifetime 'a as defined on the block at 17:63...
:17 fn get_something<'a>() -> Result<&'a Something<'a>, io::Error> {
:18 let mut something = Something::new();
:19 try!(get_lines("gates.txt"))
:20 .map(|line| line.unwrap().as_ref())
:21 .map(|line| something.insert(line, line));
:22 Ok(&something)
...
:18:39: 23:2 note: ...but borrowed value is only valid for the block suffix following statement 0 at 18:38
:18 let mut something = Something::new();
:19 try!(get_lines("gates.txt"))
:20 .map(|line| line.unwrap().as_ref())
:21 .map(|line| something.insert(line, line));
:22 Ok(&something)
:23 }
:20:18: 20:31 error: borrowed value does not live long enough
:20 .map(|line| line.unwrap().as_ref())
^~~~~~~~~~~~~
:17:64: 23:2 note: reference must be valid for the lifetime 'a as defined on the block at 17:63...
:17 fn get_something<'a>() -> Result<&'a Something<'a>, io::Error> {
:18 let mut something = Something::new();
:19 try!(get_lines("gates.txt"))
:20 .map(|line| line.unwrap().as_ref())
:21 .map(|line| something.insert(line, line));
:22 Ok(&something)
...
:20:18: 20:40 note: ...but borrowed value is only valid for the block at 20:17
:20 .map(|line| line.unwrap().as_ref())
^~~~~~~~~~~~~~~~~~~~~~
error: aborting due to 2 previous errors
playpen: application terminated with error code 101