rust: add step5_tco

3 files changed, 252 insertions, 4 deletions

diff --git a/rust/src/step3_env.rs b/rust/src/step3_env.rs
index e0957b9..f916396 100644
--- a/rust/src/step3_env.rs
+++ b/rust/src/step3_env.rs
@@ -114,7 +114,7 @@ fn eval(ast: MalVal, env: Env) -> MalRet {
                 _ => (),
             }
             // function call
-            match eval_ast(ast, env) {
+            return match eval_ast(ast, env) {
                 Err(e) => Err(e),
                 Ok(el) => {
                     match *el {
diff --git a/rust/src/step4_if_fn_do.rs b/rust/src/step4_if_fn_do.rs
index c21ddce..9666f34 100644
--- a/rust/src/step4_if_fn_do.rs
+++ b/rust/src/step4_if_fn_do.rs
@@ -163,7 +163,7 @@ fn eval(ast: MalVal, env: Env) -> MalRet {
                 _ => (),
             }
             // function call
-            match eval_ast(ast, env.clone()) {
+            return match eval_ast(ast, env.clone()) {
                 Err(e) => Err(e),
                 Ok(el) => {
                     match *el {
@@ -184,8 +184,8 @@ fn eval(ast: MalVal, env: Env) -> MalRet {
                                     let new_env = env_new(Some(mfc.env.clone()));
                                     match env_bind(&new_env, mfc.params,
                                                              Rc::new(alst)) {
-                                        Ok(_) => return eval(mfc.exp, new_env),
-                                        Err(e) => return Err(e),
+                                        Ok(_) => eval(mfc.exp, new_env),
+                                        Err(e) => Err(e),
                                     }
                                 },
                                 _ => Err("attempt to call non-function".to_string()),
diff --git a/rust/src/step5_tco.rs b/rust/src/step5_tco.rs
new file mode 100644
index 0000000..c53702f
--- /dev/null
+++ b/rust/src/step5_tco.rs
@@ -0,0 +1,248 @@
+// support precompiled regexes in reader.rs
+#![feature(phase)]
+#[phase(plugin)]
+extern crate regex_macros;
+extern crate regex;
+
+use std::rc::Rc;
+
+use types::{MalVal,MalRet,MalFunc,MalFuncData,
+            Nil,False,Sym,List,Vector,Func};
+use env::{Env,env_new,env_bind,env_set,env_get};
+mod readline;
+mod types;
+mod reader;
+mod printer;
+mod env;
+mod core;
+
+// read
+fn read(str: String) -> MalRet {
+    reader::read_str(str)
+}
+
+// eval
+fn eval_ast(ast: MalVal, env: Env) -> MalRet {
+    let ast2 = ast.clone();
+    match *ast2 {
+    //match *ast {
+        Sym(ref sym) => {
+            env_get(env.clone(), sym.clone())
+        },
+        List(ref a) => {
+            let mut ast_vec : Vec<MalVal> = vec![];
+            for mv in a.iter() {
+                let mv2 = mv.clone();
+                match eval(mv2, env.clone()) {
+                    Ok(mv) => { ast_vec.push(mv); },
+                    Err(e) => { return Err(e); },
+                }
+            }
+            Ok(Rc::new(List(ast_vec)))
+        },
+        _ => {
+            Ok(ast)
+        }
+    }
+}
+
+fn eval(mut ast: MalVal, mut env: Env) -> MalRet {
+    'tco: loop {
+
+    //println!("eval: {}, {}", ast, env.borrow());
+    //println!("eval: {}", ast);
+    let ast2 = ast.clone();
+    let ast3 = ast.clone();
+    match *ast2 {
+        List(_) => (),  // continue
+        _ => return eval_ast(ast2, env),
+    }
+
+    // apply list
+    match *ast2 {
+        List(ref args) => {
+            if args.len() == 0 { 
+                return Ok(ast3);
+            }
+            let ref a0 = *args[0];
+            match *a0 {
+                Sym(ref a0sym) => {
+                    match a0sym.as_slice() {
+                        "def!" => {
+                            let a1 = (*args)[1].clone();
+                            let a2 = (*args)[2].clone();
+                            let res = eval(a2, env.clone());
+                            match res {
+                                Ok(r) => {
+                                    match *a1 {
+                                        Sym(ref s) => {
+                                            env_set(&env.clone(), s.clone(), r.clone());
+                                            return Ok(r);
+                                        },
+                                        _ => {
+                                            return Err("def! of non-symbol".to_string())
+                                        }
+                                    }
+                                },
+                                Err(e) => return Err(e),
+                            }
+                        },
+                        "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(ref bstr) => {
+                                                match eval(exp.clone(), let_env.clone()) {
+                                                    Ok(r) => {
+                                                        env_set(&let_env, bstr.clone(), r);
+                                                    },
+                                                    Err(e) => {
+                                                        return Err(e);
+                                                    },
+                                                }
+                                            },
+                                            _ => {
+                                                return Err("let* with non-symbol binding".to_string());
+                                            },
+                                        }
+                                    }
+                                },
+                                _ => return Err("let* with non-list bindings".to_string()),
+                            }
+                            ast = a2;
+                            env = let_env.clone();
+                            continue 'tco;
+                        },
+                        "do" => {
+                            let el = Rc::new(List(args.slice(1,args.len()-1).to_vec()));
+                            match eval_ast(el, env.clone()) {
+                                Err(e) => return Err(e),
+                                Ok(_) => {
+                                    let ref last = args[args.len()-1];
+                                    ast = last.clone();
+                                    env = env.clone();
+                                    continue 'tco;
+                                },
+                            }
+                        },
+                        "if" => {
+                            let a1 = (*args)[1].clone();
+                            let cond = eval(a1, env.clone());
+                            if cond.is_err() { return cond; }
+                            match *cond.unwrap() {
+                                False | Nil => {
+                                    if args.len() >= 4 {
+                                        let a3 = (*args)[3].clone();
+                                        ast = a3;
+                                        env = env.clone();
+                                        continue 'tco;
+                                    } else {
+                                        return Ok(Rc::new(Nil));
+                                    }
+                                },
+                                _ => {
+                                    let a2 = (*args)[2].clone();
+                                    ast = a2;
+                                    env = env.clone();
+                                    continue 'tco;
+                                },
+                            }
+                        },
+                        "fn*" => {
+                            let a1 = (*args)[1].clone();
+                            let a2 = (*args)[2].clone();
+                            return Ok(Rc::new(MalFunc(MalFuncData{
+                                exp: a2,
+                                env: env.clone(),
+                                params: a1})));
+                        },
+                        _ => ()
+                    }
+                }
+                _ => (),
+            }
+            // function call
+            return match eval_ast(ast3, env.clone()) {
+                Err(e) => Err(e),
+                Ok(el) => {
+                    match *el {
+                        List(ref args) => {
+                            // TODO: make this work
+                            //match args.as_slice() {
+                            //    [&Func(f), rest..] => {
+                            //        (*f)(rest.to_vec())
+                            //    },
+                            //    _ => Err("attempt to call non-function".to_string()),
+                            //}
+                            let args2 = args.clone();
+                            match *args2[0] {
+                                Func(f) => f(args.slice(1,args.len()).to_vec()),
+                                MalFunc(ref mf) => {
+                                    let mfc = mf.clone();
+                                    let alst = List(args.slice(1,args.len()).to_vec());
+                                    let new_env = env_new(Some(mfc.env.clone()));
+                                    match env_bind(&new_env, mfc.params,
+                                                             Rc::new(alst)) {
+                                        Ok(_) => {
+                                            ast = mfc.exp;
+                                            env = new_env;
+                                            continue 'tco;
+                                        },
+                                        Err(e) => Err(e),
+                                    }
+                                },
+                                _ => Err("attempt to call non-function".to_string()),
+                            }
+                        }
+                        _ => Err("Invalid apply".to_string()),
+                    }
+                }
+            }
+        }
+        _ => return Err("Expected list".to_string()),
+    }
+
+    }
+}
+
+// print
+fn print(exp: MalVal) -> String {
+    exp.pr_str(true)
+}
+
+fn rep(str: String, env: Env) -> Result<String,String> {
+    match read(str) {
+        Err(e) => Err(e),
+        Ok(ast) => {
+            //println!("read: {}", ast);
+            match eval(ast, env) {
+                Err(e)  => Err(e),
+                Ok(exp) => Ok(print(exp)),
+            }
+        }
+    }
+}
+
+fn main() {
+    let repl_env = env_new(None);
+    for (k, v) in core::ns().into_iter() { env_set(&repl_env, k, v); }
+
+    let _ = rep("(def! not (fn* (a) (if a false true)))".to_string(),
+                repl_env.clone());
+
+    loop {
+        let line = readline::mal_readline("user> ");
+        match line { None => break, _ => () }
+        match rep(line.unwrap(), repl_env.clone()) {
+            Ok(str)  => println!("{}", str),
+            Err(str) => println!("Error: {}", str),
+        }
+    }
+}