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#![feature(exit_status)]
extern crate mal;
use std::collections::HashMap;
use std::env as stdenv;
use mal::types::{MalVal, MalRet, MalError, err_str};
use mal::types::{symbol, _nil, string, list, vector, hash_map, malfunc};
use mal::types::MalError::{ErrString, ErrMalVal};
use mal::types::MalType::{Nil, False, Sym, List, Vector, Hash_Map, Func, MalFunc};
use mal::{readline, reader, core};
use mal::env::{env_set, env_get, env_new, env_bind, env_root, Env};
// read
fn read(str: String) -> MalRet {
reader::read_str(str)
}
// eval
fn is_pair(x: MalVal) -> bool {
match *x {
List(ref lst,_) | Vector(ref lst,_) => lst.len() > 0,
_ => false,
}
}
fn quasiquote(ast: MalVal) -> MalVal {
if !is_pair(ast.clone()) {
return list(vec![symbol("quote"), ast])
}
match *ast.clone() {
List(ref args,_) | Vector(ref args,_) => {
let ref a0 = args[0];
match **a0 {
Sym(ref s) if *s == "unquote" => return args[1].clone(),
_ => (),
}
if is_pair(a0.clone()) {
match **a0 {
List(ref a0args,_) | Vector(ref a0args,_) => {
match *a0args[0] {
Sym(ref s) if *s == "splice-unquote" => {
return list(vec![symbol("concat"),
a0args[1].clone(),
quasiquote(list(args[1..].to_vec()))])
},
_ => (),
}
},
_ => (),
}
}
let rest = list(args[1..].to_vec());
return list(vec![symbol("cons"),
quasiquote(a0.clone()),
quasiquote(rest)])
},
_ => _nil(), // should never reach
}
}
fn eval_ast(ast: MalVal, env: Env) -> MalRet {
match *ast {
Sym(_) => env_get(&env, &ast),
List(ref a,_) | Vector(ref a,_) => {
let mut ast_vec : Vec<MalVal> = vec![];
for mv in a.iter() {
let mv2 = mv.clone();
ast_vec.push(try!(eval(mv2, env.clone())));
}
Ok(match *ast { List(_,_) => list(ast_vec),
_ => vector(ast_vec) })
}
Hash_Map(ref hm,_) => {
let mut new_hm: HashMap<String,MalVal> = HashMap::new();
for (key, value) in hm.iter() {
new_hm.insert(key.to_string(),
try!(eval(value.clone(), env.clone())));
}
Ok(hash_map(new_hm))
}
_ => Ok(ast.clone()),
}
}
fn eval(mut ast: MalVal, mut env: Env) -> MalRet {
'tco: loop {
//println!("eval: {}, {}", ast, env.borrow());
//println!("eval: {}", ast);
match *ast {
List(_,_) => (), // continue
_ => return eval_ast(ast, env),
}
// apply list
match *ast {
List(_,_) => (), // continue
_ => return Ok(ast),
}
let tmp = ast;
let (args, a0sym) = match *tmp {
List(ref args,_) => {
if args.len() == 0 {
return Ok(tmp.clone());
}
let ref a0 = *args[0];
match *a0 {
Sym(ref a0sym) => (args, &a0sym[..]),
_ => (args, "__<fn*>__"),
}
},
_ => return err_str("Expected list"),
};
match a0sym {
"def!" => {
let a1 = (*args)[1].clone();
let a2 = (*args)[2].clone();
let r = try!(eval(a2, env.clone()));
match *a1 {
Sym(_) => {
env_set(&env.clone(), a1, r.clone());
return Ok(r);
},
_ => return err_str("def! of non-symbol"),
}
},
"let*" => {
let let_env = env_new(Some(env.clone()));
let a1 = (*args)[1].clone();
let a2 = (*args)[2].clone();
match *a1 {
List(ref binds,_) | Vector(ref binds,_) => {
let mut it = binds.iter();
while it.len() >= 2 {
let b = it.next().unwrap();
let exp = it.next().unwrap();
match **b {
Sym(_) => {
let r = try!(eval(exp.clone(), let_env.clone()));
env_set(&let_env, b.clone(), r);
},
_ => return err_str("let* with non-symbol binding"),
}
}
},
_ => return err_str("let* with non-list bindings"),
}
ast = a2;
env = let_env.clone();
continue 'tco;
},
"quote" => return Ok((*args)[1].clone()),
"quasiquote" => {
let a1 = (*args)[1].clone();
ast = quasiquote(a1);
continue 'tco;
},
"do" => {
let el = list(args[1..args.len()-1].to_vec());
try!(eval_ast(el, env.clone()));
ast = args[args.len() - 1].clone();
continue 'tco;
},
"if" => {
let a1 = (*args)[1].clone();
let c = try!(eval(a1, env.clone()));
match *c {
False | Nil => {
if args.len() >= 4 {
ast = args[3].clone();
continue 'tco;
} else {
return Ok(_nil());
}
},
_ => {
ast = args[2].clone();
continue 'tco;
},
}
},
"fn*" => {
let a1 = args[1].clone();
let a2 = args[2].clone();
return Ok(malfunc(eval, a2, env, a1, _nil()));
},
"eval" => {
let a1 = (*args)[1].clone();
ast = try!(eval(a1, env.clone()));
env = env_root(&env);
continue 'tco;
},
_ => { // function call
let el = try!(eval_ast(tmp.clone(), env.clone()));
let args = match *el {
List(ref args,_) => args,
_ => return err_str("Invalid apply"),
};
return match *args.clone()[0] {
Func(f,_) => f(args[1..].to_vec()),
MalFunc(ref mf,_) => {
let mfc = mf.clone();
let alst = list(args[1..].to_vec());
let new_env = env_new(Some(mfc.env.clone()));
match env_bind(&new_env, mfc.params, alst) {
Ok(_) => {
ast = mfc.exp;
env = new_env;
continue 'tco;
},
Err(e) => err_str(&e),
}
},
_ => err_str("attempt to call non-function"),
}
},
}
}
}
// print
fn print(exp: MalVal) -> String {
exp.pr_str(true)
}
fn rep(str: &str, env: Env) -> Result<String,MalError> {
let ast = try!(read(str.to_string()));
//println!("read: {}", ast);
let exp = try!(eval(ast, env));
Ok(print(exp))
}
fn main() {
// core.rs: defined using rust
let repl_env = env_new(None);
for (k, v) in core::ns().into_iter() {
env_set(&repl_env, symbol(&k), v);
}
// see eval() for definition of "eval"
env_set(&repl_env, symbol("*ARGV*"), list(vec![]));
// core.mal: defined using the language itself
let _ = rep("(def! not (fn* (a) (if a false true)))", repl_env.clone());
let _ = rep("(def! load-file (fn* (f) (eval (read-string (str \"(do \" (slurp f) \")\")))))", repl_env.clone());
// Invoked with command line arguments
let args = stdenv::args();
if args.len() > 1 {
let mv_args = args.skip(2)
.map(|a| string(a))
.collect::<Vec<MalVal>>();
env_set(&repl_env, symbol("*ARGV*"), list(mv_args));
let lf = format!("(load-file \"{}\")",
stdenv::args().skip(1).next().unwrap());
return match rep(&lf, repl_env.clone()) {
Ok(_) => stdenv::set_exit_status(0),
Err(str) => {
println!("Error: {:?}", str);
stdenv::set_exit_status(1);
}
};
}
// repl loop
loop {
let line = readline::mal_readline("user> ");
match line { None => break, _ => () }
match rep(&line.unwrap(), repl_env.clone()) {
Ok(str) => println!("{}", str),
Err(ErrMalVal(_)) => (), // Blank line
Err(ErrString(s)) => println!("Error: {}", s),
}
}
}
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