Makes variadic arguments truly optional (you can pass zero of them)

helpers.go

@@ -576,19 +576,18 @@ func stringParensMatch(s string) bool {
 	return true
 }
 
-func variadic(l expression) int {
-	list, ok := l.([]expression)
-	if !ok || len(list) == 0 {
-		return 0
+func variadic(l []expression) int {
+	args := len(l)
+	variadic := false
+	for _, v := range l {
+		if arg, ok := v.(symbol); ok && (arg == symbol("args-list") || arg == symbol("...")) {
+			variadic = true
+		}
+		if variadic {
+			args -= 1
+		}
 	}
-	v, ok := list[len(list)-1].(symbol)
-	if !ok {
-		return 0
-	}
-	if v == symbol("args-list") {
-		return 1
-	}
-	return 0
+	return args
 }
 
 func completeFromMap(m map[string]string, input string, index int) (c []string) {

interpreter.go

@@ -446,7 +446,8 @@ func apply(procedure expression, args []expression) (value expression) {
 		en := &env{make(vars), p.en}
 		switch params := p.params.(type) {
 		case []expression:
-			if len(params)-variadic(params) > len(args) {
+			fmt.Println(p)
+			if variadic(params) > len(args) {
 				return exception(fmt.Sprintf("Lambda expected %d arguments but received %d", len(params), len(args)))
 			}
 			for i, param := range params {

main.go

@@ -16,7 +16,7 @@ import (
 	ln "github.com/peterh/liner"
 )
 
-const version = "0.6.4"
+const version = "0.7.0"
 
 const globalLibPath = "/usr/local/lib/slope/modules/"