build

$ cargo build
   Compiling phfoo v0.1.0 (file:///home/clint/src/rustplay/phf/phfoo)
error[E0463]: can't find crate for `phf_macros`
 --> src/main.rs:2:11
  |
2 | #![plugin(phf_macros)]
  |           ^^^^^^^^^^ can't find crate

error: aborting due to previous error

error: Could not compile `phfoo`.

To learn more, run the command again with --verbose.

main.rs

#![feature(plugin)]
#![plugin(phf_macros)]

extern crate phf;

#[derive(Clone)]
pub enum Keyword {
    Loop,
    Continue,
    Break,
    Fn,
    Extern,
}

static KEYWORDS: phf::Map<&'static str, Keyword> = phf_map! {
    "loop" => Keyword::Loop,
    "continue" => Keyword::Continue,
    "break" => Keyword::Break,
    "fn" => Keyword::Fn,
    "extern" => Keyword::Extern,
};

pub fn parse_keyword(keyword: &str) -> Option<Keyword> {
    KEYWORDS.get(keyword).cloned()
}

fn main() {
    match KEYWORDS.get("loop") {
		Keyword::Loop => println!("The cow says loop"),
		_ => println!("The cow has mad cow disease"),
	}
}