diff --git a/parser/face.go b/parser/face.go
index 776f198..80368e7 100644
--- a/parser/face.go
+++ b/parser/face.go
@@ -47,11 +47,13 @@ func (parser *ParsingOperation) parseFaceSection () (
 
 	if parser.token.Is(lexer.TokenKindName) {
 		// parse type interface
+		section.kind = FaceKindType
 		parser.previousToken()
 		section.behaviors, err = parser.parseFaceBehaviors()
 		if err != nil { return }
 	} else {
 		// parse function interface
+		section.kind = FaceKindFunc
 		parser.previousToken()
 		section.inputs,
 		section.outputs, err = parser.parseFaceBehaviorArguments(1)
@@ -157,15 +159,16 @@ func (parser *ParsingOperation) parseFaceBehaviorArguments (
 		if err != nil { return }
 		declaration.what, err = parser.parseType()
 		if err != nil { return }
-		err = parser.expect(lexer.TokenKindNewline)
-		if err != nil { return }
-		err = parser.nextToken()
-		if err != nil { return }
 
 		if kind == lexer.TokenKindGreaterThan {
 			inputs = append(inputs, declaration)
 		} else {
 			outputs = append(outputs, declaration)
 		}
+		
+		err = parser.expect(lexer.TokenKindNewline)
+		if err != nil { return }
+		err = parser.nextToken()
+		if err != nil { return }
 	}
 }
diff --git a/parser/tree-tostring.go b/parser/tree-tostring.go
index 0896e16..ab75531 100644
--- a/parser/tree-tostring.go
+++ b/parser/tree-tostring.go
@@ -250,10 +250,21 @@ func (section FaceSection) ToString (indent int) (output string) {
 		section.name, ":",
 		section.inherits.ToString(), "\n")
 
-	for _, name := range sortMapKeysAlphabetically(section.behaviors) {
-		behavior := section.behaviors[name]
-		output += behavior.ToString(indent + 1)
+	if section.kind == FaceKindType {
+		for _, name := range sortMapKeysAlphabetically(section.behaviors) {
+			behavior := section.behaviors[name]
+			output += behavior.ToString(indent + 1)
+		}
+	} else if section.kind == FaceKindFunc {
+		for _, inputItem := range section.inputs {
+			output += doIndent(indent + 1, "> ", inputItem.ToString(), "\n")
+		}
+		
+		for _, outputItem := range section.outputs {
+			output += doIndent(indent + 1, "< ", outputItem.ToString(), "\n")
+		}
 	}
+
 	return
 }
 
diff --git a/parser/tree.go b/parser/tree.go
index 35eb8fd..f46e053 100644
--- a/parser/tree.go
+++ b/parser/tree.go
@@ -196,7 +196,8 @@ type EnumSection struct {
 type FaceKind int
 
 const (
-	FaceKindType FaceKind = iota
+	FaceKindEmpty FaceKind = iota
+	FaceKindType
 	FaceKindFunc
 )