rust/src/step1_read_print.rs

   1 // support precompiled regexes in reader.rs
   2 #![feature(phase)]
   3 #[phase(plugin)]
   4 extern crate regex_macros;
   5 extern crate regex;
   6
   7 use types::{MalVal,MalRet,MalError,ErrString,ErrMalVal};
   8 mod readline;
   9 mod types;
  10 mod env;
  11 mod reader;
  12 mod printer;
  13
  14 // read
  15 fn read(str: String) -> MalRet {
  16     reader::read_str(str)
  17 }
  18
  19 // eval
  20 fn eval(ast: MalVal) -> MalRet {
  21     Ok(ast)
  22 }
  23
  24 // print
  25 fn print(exp: MalVal) -> String {
  26     exp.pr_str(true)
  27 }
  28
  29 fn rep(str: String) -> Result<String,MalError> {
  30     match read(str) {
  31         Err(e) => Err(e),
  32         Ok(ast) => {
  33             //println!("read: {}", ast);
  34             match eval(ast) {
  35                 Err(e)  => Err(e),
  36                 Ok(exp) => Ok(print(exp)),
  37             }
  38         }
  39     }
  40 }
  41
  42 fn main() {
  43     loop {
  44         let line = readline::mal_readline("user> ");
  45         match line { None => break, _ => () }
  46         match rep(line.unwrap()) {
  47             Ok(str)  => println!("{}", str),
  48             Err(ErrMalVal(_)) => (),  // Blank line
  49             Err(ErrString(s)) => println!("Error: {}", s),
  50         }
  51     }
  52 }