eval: add len

ast/ast.go

@@ -94,14 +94,14 @@ func (ast *AST) Pretty() string {
 			rest = " . " + *val.Rest
 		}
 		// TODO: opt
-    opt := ""
+		opt := ""
 		iter := val.Opt.IterFunc()
 		for kv, ok := iter(); ok; kv, ok = iter() {
-      opt += "(o " + kv.Key.(string) + " " + kv.Value.(*AST).Pretty() + ")"
-    }
-    if val.HasOpt() && (val.HasRest() || len(agg) != 0) {
-      opt = " " + opt
-    }
+			opt += "(o " + kv.Key.(string) + " " + kv.Value.(*AST).Pretty() + ")"
+		}
+		if val.HasOpt() && (val.HasRest() || len(agg) != 0) {
+			opt = " " + opt
+		}
 		body := val.Body.Pretty()
 		return "(fn (" + strings.Join(agg, " ") + rest + opt + ") " + body + ")"
 	} else if ast.Tag == Char {
@@ -167,5 +167,5 @@ func (f *Func) HasRest() bool {
 }
 
 func (f *Func) HasOpt() bool {
-  return f.Opt.Len() != 0
+	return f.Opt.Len() != 0
 }