go: add step5_tco. Refactor env.

Move EnvType interface definition to types.go. Remove Env pointers.

1 files changed, 10 insertions, 9 deletions

diff --git a/go/src/step3_env/step3_env.go b/go/src/step3_env/step3_env.go
index 3d35dbe..68a8f0c 100644
--- a/go/src/step3_env/step3_env.go
+++ b/go/src/step3_env/step3_env.go
@@ -22,7 +22,7 @@ func READ(str string) (MalType, error) {
 }
 
 // eval
-func eval_ast(ast MalType, env Env) (MalType, error) {
+func eval_ast(ast MalType, env EnvType) (MalType, error) {
     //fmt.Printf("eval_ast: %#v\n", ast)
     if Symbol_Q(ast) {
         return env.Get(ast.(Symbol).Val)
@@ -61,7 +61,7 @@ func eval_ast(ast MalType, env Env) (MalType, error) {
     }
 }
 
-func EVAL(ast MalType, env Env) (MalType, error) {
+func EVAL(ast MalType, env EnvType) (MalType, error) {
     //fmt.Printf("EVAL: %#v\n", ast)
     switch ast.(type) {
     case List: // continue
@@ -87,7 +87,7 @@ func EVAL(ast MalType, env Env) (MalType, error) {
         if e != nil { return nil, e }
         return env.Set(a1.(Symbol).Val, res), nil
     case "let*":
-        let_env, e := NewEnv(&env, nil, nil)
+        let_env, e := NewEnv(env, nil, nil)
         if e != nil { return nil, e }
         arr1, e := GetSlice(a1)
         if e != nil { return nil, e }
@@ -95,11 +95,11 @@ func EVAL(ast MalType, env Env) (MalType, error) {
             if !Symbol_Q(arr1[i]) {
                 return nil, errors.New("non-symbol bind value")
             }
-            exp, e := EVAL(arr1[i+1], *let_env)
+            exp, e := EVAL(arr1[i+1], let_env)
             if e != nil { return nil, e }
             let_env.Set(arr1[i].(Symbol).Val, exp)
         }
-        return EVAL(a2, *let_env)
+        return EVAL(a2, let_env)
     default:
         el, e := eval_ast(ast, env)
         if e != nil { return nil, e }
@@ -110,7 +110,7 @@ func EVAL(ast MalType, env Env) (MalType, error) {
 }
 
 // print
-func PRINT(exp MalType) (MalType, error) {
+func PRINT(exp MalType) (string, error) {
     return printer.Pr_str(exp, true), nil
 }
 
@@ -120,11 +120,12 @@ var repl_env, _ = NewEnv(nil, nil, nil)
 // repl
 func rep(str string) (MalType, error) {
     var exp MalType
+    var res string
     var e error
     if exp, e = READ(str); e != nil { return nil, e }
-    if exp, e = EVAL(exp, *repl_env); e != nil { return nil, e }
-    if exp, e = PRINT(exp); e != nil { return nil, e }
-    return exp, nil
+    if exp, e = EVAL(exp, repl_env); e != nil { return nil, e }
+    if res, e = PRINT(exp); e != nil { return nil, e }
+    return res, nil
 }
 
 func main() {