all: add optional args

README.md

@@ -9,7 +9,6 @@
 - Destructuring assignment
 - `maptable`
 - `coerce`
-- `o`
 - `len`
 - `mac`
 - `\``

ast/ast.go

@@ -3,6 +3,8 @@ package ast
 import (
 	"fmt"
 	"strings"
+
+	"github.com/cevaris/ordered_map"
 )
 
 type AST struct {
@@ -88,9 +90,10 @@ func (ast *AST) Pretty() string {
 			agg = append(agg, elem)
 		}
 		opt := ""
-    if val.HasOpt() {
-      opt = " . " + *val.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 {
@@ -121,12 +124,12 @@ type Primitive struct {
 	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
 }

eval/eval.go

@@ -6,6 +6,8 @@ import (
 	"fmt"
 	"strings"
 
+	"github.com/cevaris/ordered_map"
+
 	"github.com/hellerve/argos/ast"
 )
 
@@ -264,18 +266,34 @@ func evalFn(input []*ast.AST, e ast.Env) (*ast.AST, error) {
 	}
 
 	var argsStr []string
-  var opt *string = nil
+	var rest *string = nil
+	opt := ordered_map.NewOrderedMap()
 
 	argslst := args.Val.([]*ast.AST)
 	for i, a := range argslst {
-		if a.Tag != ast.Symbol {
+		if a.Tag != ast.Symbol && a.Tag != ast.List {
 			return nil, fmt.Errorf("Argument list cannot contain %s", a.Pretty())
 		}
+
+		if a.Tag == ast.List {
+			argv := a.Val.([]*ast.AST)
+			argvln := len(argv)
+			if (argvln != 3 && argvln != 2) || argv[0].Tag != ast.Symbol || argv[0].Val.(string) != "o" || argv[0].Tag != ast.Symbol {
+				return nil, fmt.Errorf("Argument list cannot contain %s", a.Pretty())
+			}
+			if argvln == 2 {
+				opt.Set(argv[1].Val.(string), nil)
+			} else if argvln == 3 {
+				opt.Set(argv[1].Val.(string), argv[2])
+			}
+			continue
+		}
+
 		val := a.Val.(string)
 		// TODO: error handling
 		if val == "." {
 			str := argslst[i+1].Val.(string)
-      opt = &str
+			rest = &str
 			break
 		}
 
@@ -284,7 +302,9 @@ func evalFn(input []*ast.AST, e ast.Env) (*ast.AST, error) {
 
 	body := input[1]
 
-	res := ast.AST{ast.Fn, ast.Func{argsStr, opt, body, e}}
+  fe := ast.NewEnv(&e)
+
+	res := ast.AST{ast.Fn, ast.Func{argsStr, rest, opt, body, fe}}
 	return &res, nil
 }
 
@@ -292,7 +312,7 @@ func funcApply(f ast.Func, args []*ast.AST, e ast.Env) (*ast.AST, error) {
 	plen := len(f.Params)
 	alen := len(args)
 
-	if plen != alen && !f.HasOpt() {
+	if plen != alen && !f.HasRest() && !f.HasOpt() {
 		return nil, fmt.Errorf("Function expected %d arguments, was called with %d.", plen, alen)
 	}
 
@@ -300,10 +320,21 @@ func funcApply(f ast.Func, args []*ast.AST, e ast.Env) (*ast.AST, error) {
 		f.Env.Values[a] = args[i]
 	}
 
-  if f.HasOpt() {
+	if f.HasRest() {
 		lst := ast.AST{ast.List, args[plen:]}
 		quoted := ast.AST{ast.Quoted, &lst}
-    f.Env.Values[*f.Opt] = &quoted
+		f.Env.Values[*f.Rest] = &quoted
+	} else {
+		iter := f.Opt.IterFunc()
+		i := plen
+		for kv, ok := iter(); ok; kv, ok = iter() {
+			if i < alen {
+				f.Env.Values[kv.Key.(string)] = args[i]
+			} else {
+				f.Env.Values[kv.Key.(string)] = kv.Value.(*ast.AST)
+			}
+			i++
+		}
 	}
 
 	return Eval(f.Body, f.Env)