diff --git a/src/Language/AST/Argument.php b/src/Language/AST/Argument.php
index 18579f0..e840ecc 100644
--- a/src/Language/AST/Argument.php
+++ b/src/Language/AST/Argument.php
@@ -3,7 +3,7 @@ namespace GraphQL\Language\AST;
 
 class Argument extends Node
 {
-    public $kind = Node::ARGUMENT;
+    public $kind = NodeType::ARGUMENT;
 
     /**
      * @var Value
diff --git a/src/Language/AST/BooleanValue.php b/src/Language/AST/BooleanValue.php
index cc6a1b3..2e7077f 100644
--- a/src/Language/AST/BooleanValue.php
+++ b/src/Language/AST/BooleanValue.php
@@ -4,10 +4,10 @@ namespace GraphQL\Language\AST;
 
 class BooleanValue extends Node implements Value
 {
-    public $kind = Node::BOOLEAN;
+    public $kind = NodeType::BOOLEAN;
 
     /**
      * @var string
      */
     public $value;
-}
\ No newline at end of file
+}
diff --git a/src/Language/AST/Directive.php b/src/Language/AST/Directive.php
index 2b23886..b9f9d27 100644
--- a/src/Language/AST/Directive.php
+++ b/src/Language/AST/Directive.php
@@ -3,7 +3,7 @@ namespace GraphQL\Language\AST;
 
 class Directive extends Node
 {
-    public $kind = Node::DIRECTIVE;
+    public $kind = NodeType::DIRECTIVE;
 
     /**
      * @var Name
diff --git a/src/Language/AST/DirectiveDefinition.php b/src/Language/AST/DirectiveDefinition.php
index 81cd696..fb0268d 100644
--- a/src/Language/AST/DirectiveDefinition.php
+++ b/src/Language/AST/DirectiveDefinition.php
@@ -6,7 +6,7 @@ class DirectiveDefinition extends Node implements TypeSystemDefinition
     /**
      * @var string
      */
-    public $kind = Node::DIRECTIVE_DEFINITION;
+    public $kind = NodeType::DIRECTIVE_DEFINITION;
 
     /**
      * @var Name
diff --git a/src/Language/AST/Document.php b/src/Language/AST/Document.php
index 800f48b..8e74fd9 100644
--- a/src/Language/AST/Document.php
+++ b/src/Language/AST/Document.php
@@ -3,7 +3,7 @@ namespace GraphQL\Language\AST;
 
 class Document extends Node
 {
-    public $kind = Node::DOCUMENT;
+    public $kind = NodeType::DOCUMENT;
 
     /**
      * @var Definition[]
diff --git a/src/Language/AST/EnumTypeDefinition.php b/src/Language/AST/EnumTypeDefinition.php
index fc1fc39..4a46528 100644
--- a/src/Language/AST/EnumTypeDefinition.php
+++ b/src/Language/AST/EnumTypeDefinition.php
@@ -6,7 +6,7 @@ class EnumTypeDefinition extends Node implements TypeDefinition
     /**
      * @var string
      */
-    public $kind = self::ENUM_TYPE_DEFINITION;
+    public $kind = NodeType::ENUM_TYPE_DEFINITION;
 
     /**
      * @var Name
diff --git a/src/Language/AST/EnumValue.php b/src/Language/AST/EnumValue.php
index 7524735..e0c5828 100644
--- a/src/Language/AST/EnumValue.php
+++ b/src/Language/AST/EnumValue.php
@@ -3,7 +3,7 @@ namespace GraphQL\Language\AST;
 
 class EnumValue extends Node implements Value
 {
-    public $kind = Node::ENUM;
+    public $kind = NodeType::ENUM;
 
     /**
      * @var string
diff --git a/src/Language/AST/EnumValueDefinition.php b/src/Language/AST/EnumValueDefinition.php
index d1a751d..8ff4616 100644
--- a/src/Language/AST/EnumValueDefinition.php
+++ b/src/Language/AST/EnumValueDefinition.php
@@ -6,7 +6,7 @@ class EnumValueDefinition extends Node
     /**
      * @var string
      */
-    public $kind = Node::ENUM_VALUE_DEFINITION;
+    public $kind = NodeType::ENUM_VALUE_DEFINITION;
 
     /**
      * @var Name
diff --git a/src/Language/AST/Field.php b/src/Language/AST/Field.php
index 7a2f997..8f36475 100644
--- a/src/Language/AST/Field.php
+++ b/src/Language/AST/Field.php
@@ -3,7 +3,7 @@ namespace GraphQL\Language\AST;
 
 class Field extends Node implements Selection
 {
-    public $kind = Node::FIELD;
+    public $kind = NodeType::FIELD;
 
     /**
      * @var Name
diff --git a/src/Language/AST/FieldDefinition.php b/src/Language/AST/FieldDefinition.php
index 13d24b6..01026d8 100644
--- a/src/Language/AST/FieldDefinition.php
+++ b/src/Language/AST/FieldDefinition.php
@@ -6,7 +6,7 @@ class FieldDefinition extends Node
     /**
      * @var string
      */
-    public $kind = Node::FIELD_DEFINITION;
+    public $kind = NodeType::FIELD_DEFINITION;
 
     /**
      * @var Name
diff --git a/src/Language/AST/FloatValue.php b/src/Language/AST/FloatValue.php
index b29ffd3..3fa1d42 100644
--- a/src/Language/AST/FloatValue.php
+++ b/src/Language/AST/FloatValue.php
@@ -1,13 +1,12 @@
 <?php
 namespace GraphQL\Language\AST;
 
-
 class FloatValue extends Node implements Value
 {
-    public $kind = Node::FLOAT;
+    public $kind = NodeType::FLOAT;
 
     /**
      * @var string
      */
     public $value;
-}
\ No newline at end of file
+}
diff --git a/src/Language/AST/FragmentDefinition.php b/src/Language/AST/FragmentDefinition.php
index 095aa68..f48b46d 100644
--- a/src/Language/AST/FragmentDefinition.php
+++ b/src/Language/AST/FragmentDefinition.php
@@ -1,10 +1,9 @@
 <?php
 namespace GraphQL\Language\AST;
 
-
 class FragmentDefinition extends Node implements Definition, HasSelectionSet
 {
-    public $kind = Node::FRAGMENT_DEFINITION;
+    public $kind = NodeType::FRAGMENT_DEFINITION;
 
     /**
      * @var Name
diff --git a/src/Language/AST/FragmentSpread.php b/src/Language/AST/FragmentSpread.php
index ccb2798..4b9d601 100644
--- a/src/Language/AST/FragmentSpread.php
+++ b/src/Language/AST/FragmentSpread.php
@@ -3,7 +3,7 @@ namespace GraphQL\Language\AST;
 
 class FragmentSpread extends Node implements Selection
 {
-    public $kind = Node::FRAGMENT_SPREAD;
+    public $kind = NodeType::FRAGMENT_SPREAD;
 
     /**
      * @var Name
diff --git a/src/Language/AST/InlineFragment.php b/src/Language/AST/InlineFragment.php
index 9691f31..ba3f1c9 100644
--- a/src/Language/AST/InlineFragment.php
+++ b/src/Language/AST/InlineFragment.php
@@ -3,7 +3,7 @@ namespace GraphQL\Language\AST;
 
 class InlineFragment extends Node implements Selection
 {
-    public $kind = Node::INLINE_FRAGMENT;
+    public $kind = NodeType::INLINE_FRAGMENT;
 
     /**
      * @var NamedType
@@ -19,4 +19,4 @@ class InlineFragment extends Node implements Selection
      * @var SelectionSet
      */
     public $selectionSet;
-}
\ No newline at end of file
+}
diff --git a/src/Language/AST/InputObjectTypeDefinition.php b/src/Language/AST/InputObjectTypeDefinition.php
index 4c887d1..500a2a9 100644
--- a/src/Language/AST/InputObjectTypeDefinition.php
+++ b/src/Language/AST/InputObjectTypeDefinition.php
@@ -6,7 +6,7 @@ class InputObjectTypeDefinition extends Node implements TypeDefinition
     /**
      * @var string
      */
-    public $kind = Node::INPUT_OBJECT_TYPE_DEFINITION;
+    public $kind = NodeType::INPUT_OBJECT_TYPE_DEFINITION;
 
     /**
      * @var Name
diff --git a/src/Language/AST/InputValueDefinition.php b/src/Language/AST/InputValueDefinition.php
index 06af8ff..4efe932 100644
--- a/src/Language/AST/InputValueDefinition.php
+++ b/src/Language/AST/InputValueDefinition.php
@@ -6,7 +6,7 @@ class InputValueDefinition extends Node
     /**
      * @var string
      */
-    public $kind = Node::INPUT_VALUE_DEFINITION;
+    public $kind = NodeType::INPUT_VALUE_DEFINITION;
 
     /**
      * @var Name
@@ -27,4 +27,4 @@ class InputValueDefinition extends Node
      * @var Directive[]
      */
     public $directives;
-}
\ No newline at end of file
+}
diff --git a/src/Language/AST/IntValue.php b/src/Language/AST/IntValue.php
index 45cde14..60329d4 100644
--- a/src/Language/AST/IntValue.php
+++ b/src/Language/AST/IntValue.php
@@ -1,10 +1,9 @@
 <?php
 namespace GraphQL\Language\AST;
 
-
 class IntValue extends Node implements Value
 {
-    public $kind = Node::INT;
+    public $kind = NodeType::INT;
 
     /**
      * @var string
diff --git a/src/Language/AST/InterfaceTypeDefinition.php b/src/Language/AST/InterfaceTypeDefinition.php
index bdf893e..cbe7dbe 100644
--- a/src/Language/AST/InterfaceTypeDefinition.php
+++ b/src/Language/AST/InterfaceTypeDefinition.php
@@ -6,7 +6,7 @@ class InterfaceTypeDefinition extends Node implements TypeDefinition
     /**
      * @var string
      */
-    public $kind = Node::INTERFACE_TYPE_DEFINITION;
+    public $kind = NodeType::INTERFACE_TYPE_DEFINITION;
 
     /**
      * @var Name
@@ -22,4 +22,4 @@ class InterfaceTypeDefinition extends Node implements TypeDefinition
      * @var FieldDefinition[]
      */
     public $fields = [];
-}
\ No newline at end of file
+}
diff --git a/src/Language/AST/ListType.php b/src/Language/AST/ListType.php
index d75b08d..2b63f56 100644
--- a/src/Language/AST/ListType.php
+++ b/src/Language/AST/ListType.php
@@ -3,7 +3,7 @@ namespace GraphQL\Language\AST;
 
 class ListType extends Node implements Type
 {
-    public $kind = Node::LIST_TYPE;
+    public $kind = NodeType::LIST_TYPE;
 
     /**
      * @var Node
diff --git a/src/Language/AST/ListValue.php b/src/Language/AST/ListValue.php
index bb61af6..80611c6 100644
--- a/src/Language/AST/ListValue.php
+++ b/src/Language/AST/ListValue.php
@@ -1,9 +1,10 @@
 <?php
+
 namespace GraphQL\Language\AST;
 
 class ListValue extends Node implements Value
 {
-    public $kind = Node::LST;
+    public $kind = NodeType::LST;
 
     /**
      * @var array<Value>
diff --git a/src/Language/AST/Name.php b/src/Language/AST/Name.php
index e9fdb67..d3d8b8a 100644
--- a/src/Language/AST/Name.php
+++ b/src/Language/AST/Name.php
@@ -3,7 +3,7 @@ namespace GraphQL\Language\AST;
 
 class Name extends Node implements Type
 {
-    public $kind = Node::NAME;
+    public $kind = NodeType::NAME;
 
     /**
      * @var string
diff --git a/src/Language/AST/NamedType.php b/src/Language/AST/NamedType.php
index b524364..a4bc404 100644
--- a/src/Language/AST/NamedType.php
+++ b/src/Language/AST/NamedType.php
@@ -3,7 +3,7 @@ namespace GraphQL\Language\AST;
 
 class NamedType extends Node implements Type
 {
-    public $kind = Node::NAMED_TYPE;
+    public $kind = NodeType::NAMED_TYPE;
 
     /**
      * @var Name
diff --git a/src/Language/AST/Node.php b/src/Language/AST/Node.php
index 76a5b3b..16056e1 100644
--- a/src/Language/AST/Node.php
+++ b/src/Language/AST/Node.php
@@ -3,78 +3,8 @@ namespace GraphQL\Language\AST;
 
 use GraphQL\Utils;
 
-/**
- * Class Node
- * @package GraphQL\Language\AST
- */
 abstract class Node
 {
-    // constants from language/kinds.js:
-
-    const NAME = 'Name';
-
-    // Document
-
-    const DOCUMENT = 'Document';
-    const OPERATION_DEFINITION = 'OperationDefinition';
-    const VARIABLE_DEFINITION = 'VariableDefinition';
-    const VARIABLE = 'Variable';
-    const SELECTION_SET = 'SelectionSet';
-    const FIELD = 'Field';
-    const ARGUMENT = 'Argument';
-
-    // Fragments
-
-    const FRAGMENT_SPREAD = 'FragmentSpread';
-    const INLINE_FRAGMENT = 'InlineFragment';
-    const FRAGMENT_DEFINITION = 'FragmentDefinition';
-
-    // Values
-
-    const INT = 'IntValue';
-    const FLOAT = 'FloatValue';
-    const STRING = 'StringValue';
-    const BOOLEAN = 'BooleanValue';
-    const ENUM = 'EnumValue';
-    const LST = 'ListValue';
-    const OBJECT = 'ObjectValue';
-    const OBJECT_FIELD = 'ObjectField';
-
-    // Directives
-
-    const DIRECTIVE = 'Directive';
-
-    // Types
-
-    const NAMED_TYPE = 'NamedType';
-    const LIST_TYPE = 'ListType';
-    const NON_NULL_TYPE = 'NonNullType';
-
-    // Type System Definitions
-
-    const SCHEMA_DEFINITION = 'SchemaDefinition';
-    const OPERATION_TYPE_DEFINITION = 'OperationTypeDefinition';
-
-    // Type Definitions
-
-    const SCALAR_TYPE_DEFINITION = 'ScalarTypeDefinition';
-    const OBJECT_TYPE_DEFINITION = 'ObjectTypeDefinition';
-    const FIELD_DEFINITION = 'FieldDefinition';
-    const INPUT_VALUE_DEFINITION = 'InputValueDefinition';
-    const INTERFACE_TYPE_DEFINITION = 'InterfaceTypeDefinition';
-    const UNION_TYPE_DEFINITION = 'UnionTypeDefinition';
-    const ENUM_TYPE_DEFINITION = 'EnumTypeDefinition';
-    const ENUM_VALUE_DEFINITION = 'EnumValueDefinition';
-    const INPUT_OBJECT_TYPE_DEFINITION = 'InputObjectTypeDefinition';
-
-    // Type Extensions
-
-    const TYPE_EXTENSION_DEFINITION = 'TypeExtensionDefinition';
-
-    // Directive Definitions
-
-    const DIRECTIVE_DEFINITION = 'DirectiveDefinition';
-
     /**
       type Node = Name
     | Document
diff --git a/src/Language/AST/NodeType.php b/src/Language/AST/NodeType.php
new file mode 100644
index 0000000..4b73d8e
--- /dev/null
+++ b/src/Language/AST/NodeType.php
@@ -0,0 +1,72 @@
+<?php
+
+namespace GraphQL\Language\AST;
+
+class NodeType
+{
+    // constants from language/kinds.js:
+
+    const NAME = 'Name';
+
+    // Document
+
+    const DOCUMENT = 'Document';
+    const OPERATION_DEFINITION = 'OperationDefinition';
+    const VARIABLE_DEFINITION = 'VariableDefinition';
+    const VARIABLE = 'Variable';
+    const SELECTION_SET = 'SelectionSet';
+    const FIELD = 'Field';
+    const ARGUMENT = 'Argument';
+
+    // Fragments
+
+    const FRAGMENT_SPREAD = 'FragmentSpread';
+    const INLINE_FRAGMENT = 'InlineFragment';
+    const FRAGMENT_DEFINITION = 'FragmentDefinition';
+
+    // Values
+
+    const INT = 'IntValue';
+    const FLOAT = 'FloatValue';
+    const STRING = 'StringValue';
+    const BOOLEAN = 'BooleanValue';
+    const ENUM = 'EnumValue';
+    const LST = 'ListValue';
+    const OBJECT = 'ObjectValue';
+    const OBJECT_FIELD = 'ObjectField';
+
+    // Directives
+
+    const DIRECTIVE = 'Directive';
+
+    // Types
+
+    const NAMED_TYPE = 'NamedType';
+    const LIST_TYPE = 'ListType';
+    const NON_NULL_TYPE = 'NonNullType';
+
+    // Type System Definitions
+
+    const SCHEMA_DEFINITION = 'SchemaDefinition';
+    const OPERATION_TYPE_DEFINITION = 'OperationTypeDefinition';
+
+    // Type Definitions
+
+    const SCALAR_TYPE_DEFINITION = 'ScalarTypeDefinition';
+    const OBJECT_TYPE_DEFINITION = 'ObjectTypeDefinition';
+    const FIELD_DEFINITION = 'FieldDefinition';
+    const INPUT_VALUE_DEFINITION = 'InputValueDefinition';
+    const INTERFACE_TYPE_DEFINITION = 'InterfaceTypeDefinition';
+    const UNION_TYPE_DEFINITION = 'UnionTypeDefinition';
+    const ENUM_TYPE_DEFINITION = 'EnumTypeDefinition';
+    const ENUM_VALUE_DEFINITION = 'EnumValueDefinition';
+    const INPUT_OBJECT_TYPE_DEFINITION = 'InputObjectTypeDefinition';
+
+    // Type Extensions
+
+    const TYPE_EXTENSION_DEFINITION = 'TypeExtensionDefinition';
+
+    // Directive Definitions
+
+    const DIRECTIVE_DEFINITION = 'DirectiveDefinition';
+}
diff --git a/src/Language/AST/NonNullType.php b/src/Language/AST/NonNullType.php
index 857b87c..49c8c91 100644
--- a/src/Language/AST/NonNullType.php
+++ b/src/Language/AST/NonNullType.php
@@ -3,7 +3,7 @@ namespace GraphQL\Language\AST;
 
 class NonNullType extends Node implements Type
 {
-    public $kind = Node::NON_NULL_TYPE;
+    public $kind = NodeType::NON_NULL_TYPE;
 
     /**
      * @var Name | ListType
diff --git a/src/Language/AST/ObjectField.php b/src/Language/AST/ObjectField.php
index 10d0ac1..bce08e8 100644
--- a/src/Language/AST/ObjectField.php
+++ b/src/Language/AST/ObjectField.php
@@ -4,7 +4,7 @@ namespace GraphQL\Language\AST;
 
 class ObjectField extends Node
 {
-    public $kind = Node::OBJECT_FIELD;
+    public $kind = NodeType::OBJECT_FIELD;
 
     /**
      * @var Name
diff --git a/src/Language/AST/ObjectTypeDefinition.php b/src/Language/AST/ObjectTypeDefinition.php
index e28242a..d39326e 100644
--- a/src/Language/AST/ObjectTypeDefinition.php
+++ b/src/Language/AST/ObjectTypeDefinition.php
@@ -6,7 +6,7 @@ class ObjectTypeDefinition extends Node implements TypeDefinition
     /**
      * @var string
      */
-    public $kind = Node::OBJECT_TYPE_DEFINITION;
+    public $kind = NodeType::OBJECT_TYPE_DEFINITION;
 
     /**
      * @var Name
@@ -27,4 +27,4 @@ class ObjectTypeDefinition extends Node implements TypeDefinition
      * @var FieldDefinition[]
      */
     public $fields;
-}
\ No newline at end of file
+}
diff --git a/src/Language/AST/ObjectValue.php b/src/Language/AST/ObjectValue.php
index f494f8f..e3c6b22 100644
--- a/src/Language/AST/ObjectValue.php
+++ b/src/Language/AST/ObjectValue.php
@@ -3,7 +3,7 @@ namespace GraphQL\Language\AST;
 
 class ObjectValue extends Node implements Value
 {
-    public $kind = Node::OBJECT;
+    public $kind = NodeType::OBJECT;
 
     /**
      * @var array<ObjectField>
diff --git a/src/Language/AST/OperationDefinition.php b/src/Language/AST/OperationDefinition.php
index 7e05fec..2e32df5 100644
--- a/src/Language/AST/OperationDefinition.php
+++ b/src/Language/AST/OperationDefinition.php
@@ -6,7 +6,7 @@ class OperationDefinition extends Node implements Definition, HasSelectionSet
     /**
      * @var string
      */
-    public $kind = Node::OPERATION_DEFINITION;
+    public $kind = NodeType::OPERATION_DEFINITION;
 
     /**
      * @var Name
diff --git a/src/Language/AST/OperationTypeDefinition.php b/src/Language/AST/OperationTypeDefinition.php
index 39be02d..d269442 100644
--- a/src/Language/AST/OperationTypeDefinition.php
+++ b/src/Language/AST/OperationTypeDefinition.php
@@ -6,7 +6,7 @@ class OperationTypeDefinition extends Node
     /**
      * @var string
      */
-    public $kind = Node::OPERATION_TYPE_DEFINITION;
+    public $kind = NodeType::OPERATION_TYPE_DEFINITION;
 
     /**
      * One of 'query' | 'mutation' | 'subscription'
diff --git a/src/Language/AST/ScalarTypeDefinition.php b/src/Language/AST/ScalarTypeDefinition.php
index 82028ee..cfbf889 100644
--- a/src/Language/AST/ScalarTypeDefinition.php
+++ b/src/Language/AST/ScalarTypeDefinition.php
@@ -1,13 +1,12 @@
 <?php
 namespace GraphQL\Language\AST;
 
-
 class ScalarTypeDefinition extends Node implements TypeDefinition
 {
     /**
      * @var string
      */
-    public $kind = Node::SCALAR_TYPE_DEFINITION;
+    public $kind = NodeType::SCALAR_TYPE_DEFINITION;
 
     /**
      * @var Name
diff --git a/src/Language/AST/SchemaDefinition.php b/src/Language/AST/SchemaDefinition.php
index 194b14e..7ca0142 100644
--- a/src/Language/AST/SchemaDefinition.php
+++ b/src/Language/AST/SchemaDefinition.php
@@ -6,7 +6,7 @@ class SchemaDefinition extends Node implements TypeSystemDefinition
     /**
      * @var string
      */
-    public $kind = Node::SCHEMA_DEFINITION;
+    public $kind = NodeType::SCHEMA_DEFINITION;
 
     /**
      * @var Directive[]
diff --git a/src/Language/AST/SelectionSet.php b/src/Language/AST/SelectionSet.php
index cda4113..d7bfc5d 100644
--- a/src/Language/AST/SelectionSet.php
+++ b/src/Language/AST/SelectionSet.php
@@ -3,7 +3,7 @@ namespace GraphQL\Language\AST;
 
 class SelectionSet extends Node
 {
-    public $kind = Node::SELECTION_SET;
+    public $kind = NodeType::SELECTION_SET;
 
     /**
      * @var array<Selection>
diff --git a/src/Language/AST/StringValue.php b/src/Language/AST/StringValue.php
index f1e1c1c..dd5212c 100644
--- a/src/Language/AST/StringValue.php
+++ b/src/Language/AST/StringValue.php
@@ -1,13 +1,12 @@
 <?php
 namespace GraphQL\Language\AST;
 
-
 class StringValue extends Node implements Value
 {
-    public $kind = Node::STRING;
+    public $kind = NodeType::STRING;
 
     /**
      * @var string
      */
     public $value;
-}
\ No newline at end of file
+}
diff --git a/src/Language/AST/TypeExtensionDefinition.php b/src/Language/AST/TypeExtensionDefinition.php
index 7f24468..600d122 100644
--- a/src/Language/AST/TypeExtensionDefinition.php
+++ b/src/Language/AST/TypeExtensionDefinition.php
@@ -6,7 +6,7 @@ class TypeExtensionDefinition extends Node implements TypeSystemDefinition
     /**
      * @var string
      */
-    public $kind = Node::TYPE_EXTENSION_DEFINITION;
+    public $kind = NodeType::TYPE_EXTENSION_DEFINITION;
 
     /**
      * @var ObjectTypeDefinition
diff --git a/src/Language/AST/UnionTypeDefinition.php b/src/Language/AST/UnionTypeDefinition.php
index be57abf..c61baff 100644
--- a/src/Language/AST/UnionTypeDefinition.php
+++ b/src/Language/AST/UnionTypeDefinition.php
@@ -6,7 +6,7 @@ class UnionTypeDefinition extends Node implements TypeDefinition
     /**
      * @var string
      */
-    public $kind = self::UNION_TYPE_DEFINITION;
+    public $kind = NodeType::UNION_TYPE_DEFINITION;
 
     /**
      * @var Name
diff --git a/src/Language/AST/Variable.php b/src/Language/AST/Variable.php
index b7a7dfe..fc1a6d9 100644
--- a/src/Language/AST/Variable.php
+++ b/src/Language/AST/Variable.php
@@ -3,7 +3,7 @@ namespace GraphQL\Language\AST;
 
 class Variable extends Node
 {
-    public $kind = Node::VARIABLE;
+    public $kind = NodeType::VARIABLE;
 
     /**
      * @var Name
diff --git a/src/Language/AST/VariableDefinition.php b/src/Language/AST/VariableDefinition.php
index 9415b8e..ae6d702 100644
--- a/src/Language/AST/VariableDefinition.php
+++ b/src/Language/AST/VariableDefinition.php
@@ -3,7 +3,7 @@ namespace GraphQL\Language\AST;
 
 class VariableDefinition extends Node implements Definition
 {
-    public $kind = Node::VARIABLE_DEFINITION;
+    public $kind = NodeType::VARIABLE_DEFINITION;
 
     /**
      * @var Variable
diff --git a/src/Language/Printer.php b/src/Language/Printer.php
index 16b9bc5..1a34a26 100644
--- a/src/Language/Printer.php
+++ b/src/Language/Printer.php
@@ -24,6 +24,7 @@ use GraphQL\Language\AST\IntValue;
 use GraphQL\Language\AST\ListType;
 use GraphQL\Language\AST\NamedType;
 use GraphQL\Language\AST\Node;
+use GraphQL\Language\AST\NodeType;
 use GraphQL\Language\AST\NonNullType;
 use GraphQL\Language\AST\ObjectField;
 use GraphQL\Language\AST\ObjectTypeDefinition;
@@ -44,16 +45,16 @@ class Printer
     {
         return Visitor::visit($ast, [
             'leave' => [
-                Node::NAME => function($node) {
+                NodeType::NAME => function($node) {
                     return '' . $node->value;
                 },
-                Node::VARIABLE => function($node) {
+                NodeType::VARIABLE => function($node) {
                     return '$' . $node->name;
                 },
-                Node::DOCUMENT => function(Document $node) {
+                NodeType::DOCUMENT => function(Document $node) {
                     return $this->join($node->definitions, "\n\n") . "\n";
                 },
-                Node::OPERATION_DEFINITION => function(OperationDefinition $node) {
+                NodeType::OPERATION_DEFINITION => function(OperationDefinition $node) {
                     $op = $node->operation;
                     $name = $node->name;
                     $varDefs = $this->wrap('(', $this->join($node->variableDefinitions, ', '), ')');
@@ -65,28 +66,28 @@ class Printer
                         ? $selectionSet
                         : $this->join([$op, $this->join([$name, $varDefs]), $directives, $selectionSet], ' ');
                 },
-                Node::VARIABLE_DEFINITION => function(VariableDefinition $node) {
+                NodeType::VARIABLE_DEFINITION => function(VariableDefinition $node) {
                     return $node->variable . ': ' . $node->type . $this->wrap(' = ', $node->defaultValue);
                 },
-                Node::SELECTION_SET => function(SelectionSet $node) {
+                NodeType::SELECTION_SET => function(SelectionSet $node) {
                     return $this->block($node->selections);
                 },
-                Node::FIELD => function(Field $node) {
+                NodeType::FIELD => function(Field $node) {
                     return $this->join([
                         $this->wrap('', $node->alias, ': ') . $node->name . $this->wrap('(', $this->join($node->arguments, ', '), ')'),
                         $this->join($node->directives, ' '),
                         $node->selectionSet
                     ], ' ');
                 },
-                Node::ARGUMENT => function(Argument $node) {
+                NodeType::ARGUMENT => function(Argument $node) {
                     return $node->name . ': ' . $node->value;
                 },
 
                 // Fragments
-                Node::FRAGMENT_SPREAD => function(FragmentSpread $node) {
+                NodeType::FRAGMENT_SPREAD => function(FragmentSpread $node) {
                     return '...' . $node->name . $this->wrap(' ', $this->join($node->directives, ' '));
                 },
-                Node::INLINE_FRAGMENT => function(InlineFragment $node) {
+                NodeType::INLINE_FRAGMENT => function(InlineFragment $node) {
                     return $this->join([
                         "...",
                         $this->wrap('on ', $node->typeCondition),
@@ -94,46 +95,46 @@ class Printer
                         $node->selectionSet
                     ], ' ');
                 },
-                Node::FRAGMENT_DEFINITION => function(FragmentDefinition $node) {
+                NodeType::FRAGMENT_DEFINITION => function(FragmentDefinition $node) {
                     return "fragment {$node->name} on {$node->typeCondition} "
                         . $this->wrap('', $this->join($node->directives, ' '), ' ')
                         . $node->selectionSet;
                 },
 
                 // Value
-                Node::INT => function(IntValue  $node) {return $node->value;},
-                Node::FLOAT => function(FloatValue $node) {return $node->value;},
-                Node::STRING => function(StringValue $node) {return json_encode($node->value);},
-                Node::BOOLEAN => function(BooleanValue $node) {return $node->value ? 'true' : 'false';},
-                Node::ENUM => function(EnumValue $node) {return $node->value;},
-                Node::LST => function(ListValue $node) {return '[' . $this->join($node->values, ', ') . ']';},
-                Node::OBJECT => function(ObjectValue $node) {return '{' . $this->join($node->fields, ', ') . '}';},
-                Node::OBJECT_FIELD => function(ObjectField $node) {return $node->name . ': ' . $node->value;},
+                NodeType::INT => function(IntValue  $node) {return $node->value;},
+                NodeType::FLOAT => function(FloatValue $node) {return $node->value;},
+                NodeType::STRING => function(StringValue $node) {return json_encode($node->value);},
+                NodeType::BOOLEAN => function(BooleanValue $node) {return $node->value ? 'true' : 'false';},
+                NodeType::ENUM => function(EnumValue $node) {return $node->value;},
+                NodeType::LST => function(ListValue $node) {return '[' . $this->join($node->values, ', ') . ']';},
+                NodeType::OBJECT => function(ObjectValue $node) {return '{' . $this->join($node->fields, ', ') . '}';},
+                NodeType::OBJECT_FIELD => function(ObjectField $node) {return $node->name . ': ' . $node->value;},
 
                 // Directive
-                Node::DIRECTIVE => function(Directive $node) {
+                NodeType::DIRECTIVE => function(Directive $node) {
                     return '@' . $node->name . $this->wrap('(', $this->join($node->arguments, ', '), ')');
                 },
 
                 // Type
-                Node::NAMED_TYPE => function(NamedType $node) {return $node->name;},
-                Node::LIST_TYPE => function(ListType $node) {return '[' . $node->type . ']';},
-                Node::NON_NULL_TYPE => function(NonNullType $node) {return $node->type . '!';},
+                NodeType::NAMED_TYPE => function(NamedType $node) {return $node->name;},
+                NodeType::LIST_TYPE => function(ListType $node) {return '[' . $node->type . ']';},
+                NodeType::NON_NULL_TYPE => function(NonNullType $node) {return $node->type . '!';},
 
                 // Type System Definitions
-                Node::SCHEMA_DEFINITION => function(SchemaDefinition $def) {
+                NodeType::SCHEMA_DEFINITION => function(SchemaDefinition $def) {
                     return $this->join([
                         'schema',
                         $this->join($def->directives, ' '),
                         $this->block($def->operationTypes)
                     ], ' ');
                 },
-                Node::OPERATION_TYPE_DEFINITION => function(OperationTypeDefinition $def) {return $def->operation . ': ' . $def->type;},
+                NodeType::OPERATION_TYPE_DEFINITION => function(OperationTypeDefinition $def) {return $def->operation . ': ' . $def->type;},
 
-                Node::SCALAR_TYPE_DEFINITION => function(ScalarTypeDefinition $def) {
+                NodeType::SCALAR_TYPE_DEFINITION => function(ScalarTypeDefinition $def) {
                     return $this->join(['scalar', $def->name, $this->join($def->directives, ' ')], ' ');
                 },
-                Node::OBJECT_TYPE_DEFINITION => function(ObjectTypeDefinition $def) {
+                NodeType::OBJECT_TYPE_DEFINITION => function(ObjectTypeDefinition $def) {
                     return $this->join([
                         'type',
                         $def->name,
@@ -142,20 +143,20 @@ class Printer
                         $this->block($def->fields)
                     ], ' ');
                 },
-                Node::FIELD_DEFINITION => function(FieldDefinition $def) {
+                NodeType::FIELD_DEFINITION => function(FieldDefinition $def) {
                     return $def->name
                          . $this->wrap('(', $this->join($def->arguments, ', '), ')')
                          . ': ' . $def->type
                          . $this->wrap(' ', $this->join($def->directives, ' '));
                 },
-                Node::INPUT_VALUE_DEFINITION => function(InputValueDefinition $def) {
+                NodeType::INPUT_VALUE_DEFINITION => function(InputValueDefinition $def) {
                     return $this->join([
                         $def->name . ': ' . $def->type,
                         $this->wrap('= ', $def->defaultValue),
                         $this->join($def->directives, ' ')
                     ], ' ');
                 },
-                Node::INTERFACE_TYPE_DEFINITION => function(InterfaceTypeDefinition $def) {
+                NodeType::INTERFACE_TYPE_DEFINITION => function(InterfaceTypeDefinition $def) {
                     return $this->join([
                         'interface',
                         $def->name,
@@ -163,7 +164,7 @@ class Printer
                         $this->block($def->fields)
                     ], ' ');
                 },
-                Node::UNION_TYPE_DEFINITION => function(UnionTypeDefinition $def) {
+                NodeType::UNION_TYPE_DEFINITION => function(UnionTypeDefinition $def) {
                     return $this->join([
                         'union',
                         $def->name,
@@ -171,7 +172,7 @@ class Printer
                         '= ' . $this->join($def->types, ' | ')
                     ], ' ');
                 },
-                Node::ENUM_TYPE_DEFINITION => function(EnumTypeDefinition $def) {
+                NodeType::ENUM_TYPE_DEFINITION => function(EnumTypeDefinition $def) {
                     return $this->join([
                         'enum',
                         $def->name,
@@ -179,13 +180,13 @@ class Printer
                         $this->block($def->values)
                     ], ' ');
                 },
-                Node::ENUM_VALUE_DEFINITION => function(EnumValueDefinition $def) {
+                NodeType::ENUM_VALUE_DEFINITION => function(EnumValueDefinition $def) {
                     return $this->join([
                         $def->name,
                         $this->join($def->directives, ' ')
                     ], ' ');
                 },
-                Node::INPUT_OBJECT_TYPE_DEFINITION => function(InputObjectTypeDefinition $def) {
+                NodeType::INPUT_OBJECT_TYPE_DEFINITION => function(InputObjectTypeDefinition $def) {
                     return $this->join([
                         'input',
                         $def->name,
@@ -193,10 +194,10 @@ class Printer
                         $this->block($def->fields)
                     ], ' ');
                 },
-                Node::TYPE_EXTENSION_DEFINITION => function(TypeExtensionDefinition $def) {
+                NodeType::TYPE_EXTENSION_DEFINITION => function(TypeExtensionDefinition $def) {
                     return "extend {$def->definition}";
                 },
-                Node::DIRECTIVE_DEFINITION => function(DirectiveDefinition $def) {
+                NodeType::DIRECTIVE_DEFINITION => function(DirectiveDefinition $def) {
                     return 'directive @' . $def->name . $this->wrap('(', $this->join($def->arguments, ', '), ')')
                         . ' on ' . $this->join($def->locations, ' | ');
                 }
diff --git a/src/Language/Visitor.php b/src/Language/Visitor.php
index 040b030..589e720 100644
--- a/src/Language/Visitor.php
+++ b/src/Language/Visitor.php
@@ -2,6 +2,7 @@
 namespace GraphQL\Language;
 
 use GraphQL\Language\AST\Node;
+use GraphQL\Language\AST\NodeType;
 use GraphQL\Utils\TypeInfo;
 
 class VisitorOperation
@@ -48,44 +49,44 @@ class Visitor
     }
 
     public static $visitorKeys = [
-        Node::NAME => [],
-        Node::DOCUMENT => ['definitions'],
-        Node::OPERATION_DEFINITION => ['name', 'variableDefinitions', 'directives', 'selectionSet'],
-        Node::VARIABLE_DEFINITION => ['variable', 'type', 'defaultValue'],
-        Node::VARIABLE => ['name'],
-        Node::SELECTION_SET => ['selections'],
-        Node::FIELD => ['alias', 'name', 'arguments', 'directives', 'selectionSet'],
-        Node::ARGUMENT => ['name', 'value'],
-        Node::FRAGMENT_SPREAD => ['name', 'directives'],
-        Node::INLINE_FRAGMENT => ['typeCondition', 'directives', 'selectionSet'],
-        Node::FRAGMENT_DEFINITION => ['name', 'typeCondition', 'directives', 'selectionSet'],
+        NodeType::NAME => [],
+        NodeType::DOCUMENT => ['definitions'],
+        NodeType::OPERATION_DEFINITION => ['name', 'variableDefinitions', 'directives', 'selectionSet'],
+        NodeType::VARIABLE_DEFINITION => ['variable', 'type', 'defaultValue'],
+        NodeType::VARIABLE => ['name'],
+        NodeType::SELECTION_SET => ['selections'],
+        NodeType::FIELD => ['alias', 'name', 'arguments', 'directives', 'selectionSet'],
+        NodeType::ARGUMENT => ['name', 'value'],
+        NodeType::FRAGMENT_SPREAD => ['name', 'directives'],
+        NodeType::INLINE_FRAGMENT => ['typeCondition', 'directives', 'selectionSet'],
+        NodeType::FRAGMENT_DEFINITION => ['name', 'typeCondition', 'directives', 'selectionSet'],
 
-        Node::INT => [],
-        Node::FLOAT => [],
-        Node::STRING => [],
-        Node::BOOLEAN => [],
-        Node::ENUM => [],
-        Node::LST => ['values'],
-        Node::OBJECT => ['fields'],
-        Node::OBJECT_FIELD => ['name', 'value'],
-        Node::DIRECTIVE => ['name', 'arguments'],
-        Node::NAMED_TYPE => ['name'],
-        Node::LIST_TYPE => ['type'],
-        Node::NON_NULL_TYPE => ['type'],
+        NodeType::INT => [],
+        NodeType::FLOAT => [],
+        NodeType::STRING => [],
+        NodeType::BOOLEAN => [],
+        NodeType::ENUM => [],
+        NodeType::LST => ['values'],
+        NodeType::OBJECT => ['fields'],
+        NodeType::OBJECT_FIELD => ['name', 'value'],
+        NodeType::DIRECTIVE => ['name', 'arguments'],
+        NodeType::NAMED_TYPE => ['name'],
+        NodeType::LIST_TYPE => ['type'],
+        NodeType::NON_NULL_TYPE => ['type'],
 
-        Node::SCHEMA_DEFINITION => ['directives', 'operationTypes'],
-        Node::OPERATION_TYPE_DEFINITION => ['type'],
-        Node::SCALAR_TYPE_DEFINITION => ['name', 'directives'],
-        Node::OBJECT_TYPE_DEFINITION => ['name', 'interfaces', 'directives', 'fields'],
-        Node::FIELD_DEFINITION => ['name', 'arguments', 'type', 'directives'],
-        Node::INPUT_VALUE_DEFINITION => ['name', 'type', 'defaultValue', 'directives'],
-        Node::INTERFACE_TYPE_DEFINITION => [ 'name', 'directives', 'fields' ],
-        Node::UNION_TYPE_DEFINITION => [ 'name', 'directives', 'types' ],
-        Node::ENUM_TYPE_DEFINITION => [ 'name', 'directives', 'values' ],
-        Node::ENUM_VALUE_DEFINITION => [ 'name', 'directives' ],
-        Node::INPUT_OBJECT_TYPE_DEFINITION => [ 'name', 'directives', 'fields' ],
-        Node::TYPE_EXTENSION_DEFINITION => [ 'definition' ],
-        Node::DIRECTIVE_DEFINITION => [ 'name', 'arguments', 'locations' ]
+        NodeType::SCHEMA_DEFINITION => ['directives', 'operationTypes'],
+        NodeType::OPERATION_TYPE_DEFINITION => ['type'],
+        NodeType::SCALAR_TYPE_DEFINITION => ['name', 'directives'],
+        NodeType::OBJECT_TYPE_DEFINITION => ['name', 'interfaces', 'directives', 'fields'],
+        NodeType::FIELD_DEFINITION => ['name', 'arguments', 'type', 'directives'],
+        NodeType::INPUT_VALUE_DEFINITION => ['name', 'type', 'defaultValue', 'directives'],
+        NodeType::INTERFACE_TYPE_DEFINITION => [ 'name', 'directives', 'fields' ],
+        NodeType::UNION_TYPE_DEFINITION => [ 'name', 'directives', 'types' ],
+        NodeType::ENUM_TYPE_DEFINITION => [ 'name', 'directives', 'values' ],
+        NodeType::ENUM_VALUE_DEFINITION => [ 'name', 'directives' ],
+        NodeType::INPUT_OBJECT_TYPE_DEFINITION => [ 'name', 'directives', 'fields' ],
+        NodeType::TYPE_EXTENSION_DEFINITION => [ 'definition' ],
+        NodeType::DIRECTIVE_DEFINITION => [ 'name', 'arguments', 'locations' ]
     ];
 
     /**
diff --git a/tests/Language/ParserTest.php b/tests/Language/ParserTest.php
index fbc93b3..6977ba4 100644
--- a/tests/Language/ParserTest.php
+++ b/tests/Language/ParserTest.php
@@ -2,13 +2,10 @@
 namespace GraphQL\Tests\Language;
 
 use GraphQL\Language\AST\Argument;
-use GraphQL\Language\AST\Document;
 use GraphQL\Language\AST\Field;
-use GraphQL\Language\AST\IntValue;
-use GraphQL\Language\AST\Location;
 use GraphQL\Language\AST\Name;
 use GraphQL\Language\AST\Node;
-use GraphQL\Language\AST\OperationDefinition;
+use GraphQL\Language\AST\NodeType;
 use GraphQL\Language\AST\SelectionSet;
 use GraphQL\Language\AST\StringValue;
 use GraphQL\Language\Parser;
@@ -270,39 +267,39 @@ fragment $fragmentName on Type {
         };
 
         $expected = [
-            'kind' => Node::DOCUMENT,
+            'kind' => NodeType::DOCUMENT,
             'loc' => $loc(0, 41),
             'definitions' => [
                 [
-                    'kind' => Node::OPERATION_DEFINITION,
+                    'kind' => NodeType::OPERATION_DEFINITION,
                     'loc' => $loc(0, 40),
                     'operation' => 'query',
                     'name' => null,
                     'variableDefinitions' => null,
                     'directives' => [],
                     'selectionSet' => [
-                        'kind' => Node::SELECTION_SET,
+                        'kind' => NodeType::SELECTION_SET,
                         'loc' => $loc(0, 40),
                         'selections' => [
                             [
-                                'kind' => Node::FIELD,
+                                'kind' => NodeType::FIELD,
                                 'loc' => $loc(4, 38),
                                 'alias' => null,
                                 'name' => [
-                                    'kind' => Node::NAME,
+                                    'kind' => NodeType::NAME,
                                     'loc' => $loc(4, 8),
                                     'value' => 'node'
                                 ],
                                 'arguments' => [
                                     [
-                                        'kind' => Node::ARGUMENT,
+                                        'kind' => NodeType::ARGUMENT,
                                         'name' => [
-                                            'kind' => Node::NAME,
+                                            'kind' => NodeType::NAME,
                                             'loc' => $loc(9, 11),
                                             'value' => 'id'
                                         ],
                                         'value' => [
-                                            'kind' => Node::INT,
+                                            'kind' => NodeType::INT,
                                             'loc' => $loc(13, 14),
                                             'value' => '4'
                                         ],
@@ -311,15 +308,15 @@ fragment $fragmentName on Type {
                                 ],
                                 'directives' => [],
                                 'selectionSet' => [
-                                    'kind' => Node::SELECTION_SET,
+                                    'kind' => NodeType::SELECTION_SET,
                                     'loc' => $loc(16, 38),
                                     'selections' => [
                                         [
-                                            'kind' => Node::FIELD,
+                                            'kind' => NodeType::FIELD,
                                             'loc' => $loc(22, 24),
                                             'alias' => null,
                                             'name' => [
-                                                'kind' => Node::NAME,
+                                                'kind' => NodeType::NAME,
                                                 'loc' => $loc(22, 24),
                                                 'value' => 'id'
                                             ],
@@ -328,11 +325,11 @@ fragment $fragmentName on Type {
                                             'selectionSet' => null
                                         ],
                                         [
-                                            'kind' => Node::FIELD,
+                                            'kind' => NodeType::FIELD,
                                             'loc' => $loc(30, 34),
                                             'alias' => null,
                                             'name' => [
-                                                'kind' => Node::NAME,
+                                                'kind' => NodeType::NAME,
                                                 'loc' => $loc(30, 34),
                                                 'value' => 'name'
                                             ],
@@ -402,16 +399,16 @@ fragment $fragmentName on Type {
     public function testParsesListValues()
     {
         $this->assertEquals([
-            'kind' => Node::LST,
+            'kind' => NodeType::LST,
             'loc' => ['start' => 0, 'end' => 11],
             'values' => [
                 [
-                    'kind' => Node::INT,
+                    'kind' => NodeType::INT,
                     'loc' => ['start' => 1, 'end' => 4],
                     'value' => '123'
                 ],
                 [
-                    'kind' => Node::STRING,
+                    'kind' => NodeType::STRING,
                     'loc' => ['start' => 5, 'end' => 10],
                     'value' => 'abc'
                 ]
@@ -427,10 +424,10 @@ fragment $fragmentName on Type {
     public function testParsesWellKnownTypes()
     {
         $this->assertEquals([
-            'kind' => Node::NAMED_TYPE,
+            'kind' => NodeType::NAMED_TYPE,
             'loc' => ['start' => 0, 'end' => 6],
             'name' => [
-                'kind' => Node::NAME,
+                'kind' => NodeType::NAME,
                 'loc' => ['start' => 0, 'end' => 6],
                 'value' => 'String'
             ]
@@ -443,10 +440,10 @@ fragment $fragmentName on Type {
     public function testParsesCustomTypes()
     {
         $this->assertEquals([
-            'kind' => Node::NAMED_TYPE,
+            'kind' => NodeType::NAMED_TYPE,
             'loc' => ['start' => 0, 'end' => 6],
             'name' => [
-                'kind' => Node::NAME,
+                'kind' => NodeType::NAME,
                 'loc' => ['start' => 0, 'end' => 6],
                 'value' => 'MyType'
             ]
@@ -459,13 +456,13 @@ fragment $fragmentName on Type {
     public function testParsesListTypes()
     {
         $this->assertEquals([
-            'kind' => Node::LIST_TYPE,
+            'kind' => NodeType::LIST_TYPE,
             'loc' => ['start' => 0, 'end' => 8],
             'type' => [
-                'kind' => Node::NAMED_TYPE,
+                'kind' => NodeType::NAMED_TYPE,
                 'loc' => ['start' => 1, 'end' => 7],
                 'name' => [
-                    'kind' => Node::NAME,
+                    'kind' => NodeType::NAME,
                     'loc' => ['start' => 1, 'end' => 7],
                     'value' => 'MyType'
                 ]
@@ -479,13 +476,13 @@ fragment $fragmentName on Type {
     public function testParsesNonNullTypes()
     {
         $this->assertEquals([
-            'kind' => Node::NON_NULL_TYPE,
+            'kind' => NodeType::NON_NULL_TYPE,
             'loc' => ['start' => 0, 'end' => 7],
             'type' => [
-                'kind' => Node::NAMED_TYPE,
+                'kind' => NodeType::NAMED_TYPE,
                 'loc' => ['start' => 0, 'end' => 6],
                 'name' => [
-                    'kind' => Node::NAME,
+                    'kind' => NodeType::NAME,
                     'loc' => ['start' => 0, 'end' => 6],
                     'value' => 'MyType'
                 ]
@@ -499,16 +496,16 @@ fragment $fragmentName on Type {
     public function testParsesNestedTypes()
     {
         $this->assertEquals([
-            'kind' => Node::LIST_TYPE,
+            'kind' => NodeType::LIST_TYPE,
             'loc' => ['start' => 0, 'end' => 9],
             'type' => [
-                'kind' => Node::NON_NULL_TYPE,
+                'kind' => NodeType::NON_NULL_TYPE,
                 'loc' => ['start' => 1, 'end' => 8],
                 'type' => [
-                    'kind' => Node::NAMED_TYPE,
+                    'kind' => NodeType::NAMED_TYPE,
                     'loc' => ['start' => 1, 'end' => 7],
                     'name' => [
-                        'kind' => Node::NAME,
+                        'kind' => NodeType::NAME,
                         'loc' => ['start' => 1, 'end' => 7],
                         'value' => 'MyType'
                     ]
diff --git a/tests/Language/SchemaParserTest.php b/tests/Language/SchemaParserTest.php
index 2f64594..f6baf47 100644
--- a/tests/Language/SchemaParserTest.php
+++ b/tests/Language/SchemaParserTest.php
@@ -14,6 +14,7 @@ use GraphQL\Language\AST\Location;
 use GraphQL\Language\AST\Name;
 use GraphQL\Language\AST\NamedType;
 use GraphQL\Language\AST\Node;
+use GraphQL\Language\AST\NodeType;
 use GraphQL\Language\AST\NonNullType;
 use GraphQL\Language\AST\ObjectTypeDefinition;
 use GraphQL\Language\AST\ScalarTypeDefinition;
@@ -39,10 +40,10 @@ type Hello {
         $loc = function($start, $end) {return TestUtils::locArray($start, $end);};
 
         $expected = [
-            'kind' => Node::DOCUMENT,
+            'kind' => NodeType::DOCUMENT,
             'definitions' => [
                 [
-                    'kind' => Node::OBJECT_TYPE_DEFINITION,
+                    'kind' => NodeType::OBJECT_TYPE_DEFINITION,
                     'name' => $this->nameNode('Hello', $loc(6, 11)),
                     'interfaces' => [],
                     'directives' => [],
@@ -76,12 +77,12 @@ extend type Hello {
             return TestUtils::locArray($start, $end);
         };
         $expected = [
-            'kind' => Node::DOCUMENT,
+            'kind' => NodeType::DOCUMENT,
             'definitions' => [
                 [
-                    'kind' => Node::TYPE_EXTENSION_DEFINITION,
+                    'kind' => NodeType::TYPE_EXTENSION_DEFINITION,
                     'definition' => [
-                        'kind' => Node::OBJECT_TYPE_DEFINITION,
+                        'kind' => NodeType::OBJECT_TYPE_DEFINITION,
                         'name' => $this->nameNode('Hello', $loc(13, 18)),
                         'interfaces' => [],
                         'directives' => [],
@@ -117,10 +118,10 @@ type Hello {
         $doc = Parser::parse($body);
 
         $expected = [
-            'kind' => Node::DOCUMENT,
+            'kind' => NodeType::DOCUMENT,
             'definitions' => [
                 [
-                    'kind' => Node::OBJECT_TYPE_DEFINITION,
+                    'kind' => NodeType::OBJECT_TYPE_DEFINITION,
                     'name' => $this->nameNode('Hello', $loc(6,11)),
                     'interfaces' => [],
                     'directives' => [],
@@ -128,7 +129,7 @@ type Hello {
                         $this->fieldNode(
                             $this->nameNode('world', $loc(16, 21)),
                             [
-                                'kind' => Node::NON_NULL_TYPE,
+                                'kind' => NodeType::NON_NULL_TYPE,
                                 'type' => $this->typeNode('String', $loc(23, 29)),
                                 'loc' => $loc(23, 30)
                             ],
@@ -154,10 +155,10 @@ type Hello {
         $doc = Parser::parse($body);
 
         $expected = [
-            'kind' => Node::DOCUMENT,
+            'kind' => NodeType::DOCUMENT,
             'definitions' => [
                 [
-                    'kind' => Node::OBJECT_TYPE_DEFINITION,
+                    'kind' => NodeType::OBJECT_TYPE_DEFINITION,
                     'name' => $this->nameNode('Hello', $loc(5, 10)),
                     'interfaces' => [
                         $this->typeNode('World', $loc(22, 27))
@@ -183,10 +184,10 @@ type Hello {
         $doc = Parser::parse($body);
 
         $expected = [
-            'kind' => Node::DOCUMENT,
+            'kind' => NodeType::DOCUMENT,
             'definitions' => [
                 [
-                    'kind' => Node::OBJECT_TYPE_DEFINITION,
+                    'kind' => NodeType::OBJECT_TYPE_DEFINITION,
                     'name' => $this->nameNode('Hello', $loc(5, 10)),
                     'interfaces' => [
                         $this->typeNode('Wo', $loc(22,24)),
@@ -213,10 +214,10 @@ type Hello {
         $doc = Parser::parse($body);
 
         $expected = [
-            'kind' => Node::DOCUMENT,
+            'kind' => NodeType::DOCUMENT,
             'definitions' => [
                 [
-                    'kind' => Node::ENUM_TYPE_DEFINITION,
+                    'kind' => NodeType::ENUM_TYPE_DEFINITION,
                     'name' => $this->nameNode('Hello', $loc(5, 10)),
                     'directives' => [],
                     'values' => [$this->enumValueNode('WORLD', $loc(13, 18))],
@@ -239,10 +240,10 @@ type Hello {
         $doc = Parser::parse($body);
 
         $expected = [
-            'kind' => Node::DOCUMENT,
+            'kind' => NodeType::DOCUMENT,
             'definitions' => [
                 [
-                    'kind' => Node::ENUM_TYPE_DEFINITION,
+                    'kind' => NodeType::ENUM_TYPE_DEFINITION,
                     'name' => $this->nameNode('Hello', $loc(5, 10)),
                     'directives' => [],
                     'values' => [
@@ -271,10 +272,10 @@ interface Hello {
         $loc = function($start, $end) {return TestUtils::locArray($start, $end);};
 
         $expected = [
-            'kind' => Node::DOCUMENT,
+            'kind' => NodeType::DOCUMENT,
             'definitions' => [
                 [
-                    'kind' => Node::INTERFACE_TYPE_DEFINITION,
+                    'kind' => NodeType::INTERFACE_TYPE_DEFINITION,
                     'name' => $this->nameNode('Hello', $loc(11, 16)),
                     'directives' => [],
                     'fields' => [
@@ -305,10 +306,10 @@ type Hello {
         $loc = function($start, $end) {return TestUtils::locArray($start, $end);};
 
         $expected = [
-            'kind' => Node::DOCUMENT,
+            'kind' => NodeType::DOCUMENT,
             'definitions' => [
                 [
-                    'kind' => Node::OBJECT_TYPE_DEFINITION,
+                    'kind' => NodeType::OBJECT_TYPE_DEFINITION,
                     'name' => $this->nameNode('Hello', $loc(6, 11)),
                     'interfaces' => [],
                     'directives' => [],
@@ -349,10 +350,10 @@ type Hello {
         $loc = function($start, $end) {return TestUtils::locArray($start, $end);};
 
         $expected = [
-            'kind' => Node::DOCUMENT,
+            'kind' => NodeType::DOCUMENT,
             'definitions' => [
                 [
-                    'kind' => Node::OBJECT_TYPE_DEFINITION,
+                    'kind' => NodeType::OBJECT_TYPE_DEFINITION,
                     'name' => $this->nameNode('Hello', $loc(6, 11)),
                     'interfaces' => [],
                     'directives' => [],
@@ -364,7 +365,7 @@ type Hello {
                                 $this->inputValueNode(
                                     $this->nameNode('flag', $loc(22, 26)),
                                     $this->typeNode('Boolean', $loc(28, 35)),
-                                    ['kind' => Node::BOOLEAN, 'value' => true, 'loc' => $loc(38, 42)],
+                                    ['kind' => NodeType::BOOLEAN, 'value' => true, 'loc' => $loc(38, 42)],
                                     $loc(22, 42)
                                 )
                             ],
@@ -392,10 +393,10 @@ type Hello {
         $loc = function($start, $end) {return TestUtils::locArray($start, $end);};
 
         $expected = [
-            'kind' => Node::DOCUMENT,
+            'kind' => NodeType::DOCUMENT,
             'definitions' => [
                 [
-                    'kind' => Node::OBJECT_TYPE_DEFINITION,
+                    'kind' => NodeType::OBJECT_TYPE_DEFINITION,
                     'name' => $this->nameNode('Hello', $loc(6, 11)),
                     'interfaces' => [],
                     'directives' => [],
@@ -406,7 +407,7 @@ type Hello {
                             [
                                 $this->inputValueNode(
                                     $this->nameNode('things', $loc(22,28)),
-                                    ['kind' => Node::LIST_TYPE, 'type' => $this->typeNode('String', $loc(31, 37)), 'loc' => $loc(30, 38)],
+                                    ['kind' => NodeType::LIST_TYPE, 'type' => $this->typeNode('String', $loc(31, 37)), 'loc' => $loc(30, 38)],
                                     null,
                                     $loc(22, 38)
                                 )
@@ -436,10 +437,10 @@ type Hello {
         $loc = function($start, $end) {return TestUtils::locArray($start, $end);};
 
         $expected = [
-            'kind' => Node::DOCUMENT,
+            'kind' => NodeType::DOCUMENT,
             'definitions' => [
                 [
-                    'kind' => Node::OBJECT_TYPE_DEFINITION,
+                    'kind' => NodeType::OBJECT_TYPE_DEFINITION,
                     'name' => $this->nameNode('Hello', $loc(6, 11)),
                     'interfaces' => [],
                     'directives' => [],
@@ -482,10 +483,10 @@ type Hello {
         $doc = Parser::parse($body);
         $loc = function($start, $end) {return TestUtils::locArray($start, $end);};
         $expected = [
-            'kind' => Node::DOCUMENT,
+            'kind' => NodeType::DOCUMENT,
             'definitions' => [
                 [
-                    'kind' => Node::UNION_TYPE_DEFINITION,
+                    'kind' => NodeType::UNION_TYPE_DEFINITION,
                     'name' => $this->nameNode('Hello', $loc(6, 11)),
                     'directives' => [],
                     'types' => [$this->typeNode('World', $loc(14, 19))],
@@ -508,10 +509,10 @@ type Hello {
         $loc = function($start, $end) {return TestUtils::locArray($start, $end);};
 
         $expected = [
-            'kind' => Node::DOCUMENT,
+            'kind' => NodeType::DOCUMENT,
             'definitions' => [
                 [
-                    'kind' => Node::UNION_TYPE_DEFINITION,
+                    'kind' => NodeType::UNION_TYPE_DEFINITION,
                     'name' => $this->nameNode('Hello', $loc(6, 11)),
                     'directives' => [],
                     'types' => [
@@ -535,10 +536,10 @@ type Hello {
         $doc = Parser::parse($body);
         $loc = function($start, $end) {return TestUtils::locArray($start, $end);};
         $expected = [
-            'kind' => Node::DOCUMENT,
+            'kind' => NodeType::DOCUMENT,
             'definitions' => [
                 [
-                    'kind' => Node::SCALAR_TYPE_DEFINITION,
+                    'kind' => NodeType::SCALAR_TYPE_DEFINITION,
                     'name' => $this->nameNode('Hello', $loc(7, 12)),
                     'directives' => [],
                     'loc' => $loc(0, 12)
@@ -562,10 +563,10 @@ input Hello {
         $loc = function($start, $end) {return TestUtils::locArray($start, $end);};
 
         $expected = [
-            'kind' => Node::DOCUMENT,
+            'kind' => NodeType::DOCUMENT,
             'definitions' => [
                 [
-                    'kind' => Node::INPUT_OBJECT_TYPE_DEFINITION,
+                    'kind' => NodeType::INPUT_OBJECT_TYPE_DEFINITION,
                     'name' => $this->nameNode('Hello', $loc(7, 12)),
                     'directives' => [],
                     'fields' => [
@@ -600,8 +601,8 @@ input Hello {
     private function typeNode($name, $loc)
     {
         return [
-            'kind' => Node::NAMED_TYPE,
-            'name' => ['kind' => Node::NAME, 'value' => $name, 'loc' => $loc],
+            'kind' => NodeType::NAMED_TYPE,
+            'name' => ['kind' => NodeType::NAME, 'value' => $name, 'loc' => $loc],
             'loc' => $loc
         ];
     }
@@ -609,7 +610,7 @@ input Hello {
     private function nameNode($name, $loc)
     {
         return [
-            'kind' => Node::NAME,
+            'kind' => NodeType::NAME,
             'value' => $name,
             'loc' => $loc
         ];
@@ -623,7 +624,7 @@ input Hello {
     private function fieldNodeWithArgs($name, $type, $args, $loc)
     {
         return [
-            'kind' => Node::FIELD_DEFINITION,
+            'kind' => NodeType::FIELD_DEFINITION,
             'name' => $name,
             'arguments' => $args,
             'type' => $type,
@@ -635,7 +636,7 @@ input Hello {
     private function enumValueNode($name, $loc)
     {
         return [
-            'kind' => Node::ENUM_VALUE_DEFINITION,
+            'kind' => NodeType::ENUM_VALUE_DEFINITION,
             'name' => $this->nameNode($name, $loc),
             'directives' => [],
             'loc' => $loc
@@ -645,7 +646,7 @@ input Hello {
     private function inputValueNode($name, $type, $defaultValue, $loc)
     {
         return [
-            'kind' => Node::INPUT_VALUE_DEFINITION,
+            'kind' => NodeType::INPUT_VALUE_DEFINITION,
             'name' => $name,
             'type' => $type,
             'defaultValue' => $defaultValue,