all: add optional args

ast/ast.go

@@ -3,6 +3,8 @@ package ast
 import (
 	"fmt"
 	"strings"
+
+	"github.com/cevaris/ordered_map"
 )
 
 type AST struct {
@@ -21,8 +23,8 @@ const (
 	Fn
 	Char
 	Table
-  Prim
-  Quoted
+	Prim
+	Quoted
 )
 
 func (tag Tag) String() string {
@@ -56,20 +58,20 @@ func (ast *AST) Type() *AST {
 		"cons",
 	}
 
-  if ast.Tag == Quoted {
-    return ast.Val.(*AST).Type()
-  }
+	if ast.Tag == Quoted {
+		return ast.Val.(*AST).Type()
+	}
 
-  name := names[ast.Tag]
-  if ast.Tag == Num {
-    val := ast.Val.(float64)
-    if val == float64(int64(val)) {
-      name = "int"
-    }
-  }
+	name := names[ast.Tag]
+	if ast.Tag == Num {
+		val := ast.Val.(float64)
+		if val == float64(int64(val)) {
+			name = "int"
+		}
+	}
 
-  res := AST{Symbol, name}
-  return &res
+	res := AST{Symbol, name}
+	return &res
 }
 
 func (ast *AST) Pretty() string {
@@ -87,11 +89,12 @@ func (ast *AST) Pretty() string {
 		for _, elem := range val.Params {
 			agg = append(agg, elem)
 		}
-    opt := ""
-    if val.HasOpt() {
-      opt = " . " + *val.Opt
-    }
-    body := val.Body.Pretty()
+		opt := ""
+		if val.HasRest() {
+			opt = " . " + *val.Rest
+		}
+		// TODO: opt
+		body := val.Body.Pretty()
 		return "(fn (" + strings.Join(agg, " ") + opt + ") " + body + ")"
 	} else if ast.Tag == Char {
 		return "#" + string(ast.Val.(rune))
@@ -104,8 +107,8 @@ func (ast *AST) Pretty() string {
 
 		return "#hash(" + strings.Join(agg, " ") + ")"
 	} else if ast.Tag == Prim {
-    return "#<procedure: " + ast.Val.(Primitive).Name + ">"
-  }
+		return "#<procedure: " + ast.Val.(Primitive).Name + ">"
+	}
 	return fmt.Sprintf("%v", ast.Val)
 }
 
@@ -117,16 +120,16 @@ type Env struct {
 type PrimFn func([]*AST) (*AST, error)
 
 type Primitive struct {
-  Name string
-  Fn PrimFn
+	Name string
+	Fn   PrimFn
 }
 
-func newEnv(parent *Env) Env {
+func NewEnv(parent *Env) Env {
 	return Env{parent, make(map[string]*AST)}
 }
 
 func ParentEnv() Env {
-	return newEnv(nil)
+	return NewEnv(nil)
 }
 
 func (e *Env) Lookup(elem string) (*AST, error) {
@@ -145,11 +148,16 @@ func (e *Env) Lookup(elem string) (*AST, error) {
 
 type Func struct {
 	Params []string
-  Opt    *string
+	Rest   *string
+	Opt    *ordered_map.OrderedMap
 	Body   *AST
 	Env    Env
 }
 
-func (f *Func) HasOpt() bool {
-  return f.Opt != nil
+func (f *Func) HasRest() bool {
+	return f.Rest != nil
+}
+
+func (f *Func) HasOpt() bool {
+  return f.Opt.Len() != 0
 }