diff --git a/integrationTests/ts/package.json b/integrationTests/ts/package.json
index 9abb028334..751644900a 100644
--- a/integrationTests/ts/package.json
+++ b/integrationTests/ts/package.json
@@ -6,9 +6,6 @@
   },
   "dependencies": {
     "graphql": "file:../graphql.tgz",
-    "typescript-3.8": "npm:typescript@3.8.x",
-    "typescript-3.9": "npm:typescript@3.9.x",
-    "typescript-4.0": "npm:typescript@4.0.x",
     "typescript-4.1": "npm:typescript@4.1.x",
     "typescript-4.2": "npm:typescript@4.2.x",
     "typescript-4.3": "npm:typescript@4.3.x",
diff --git a/src/language/ast.ts b/src/language/ast.ts
index af2b7fd7ee..fa2ac75e57 100644
--- a/src/language/ast.ts
+++ b/src/language/ast.ts
@@ -184,57 +184,15 @@ export type ASTNode =
 /**
  * Utility type listing all nodes indexed by their kind.
  */
-export interface ASTKindToNode {
-  Name: NameNode;
-  Document: DocumentNode;
-  OperationDefinition: OperationDefinitionNode;
-  VariableDefinition: VariableDefinitionNode;
-  Variable: VariableNode;
-  SelectionSet: SelectionSetNode;
-  Field: FieldNode;
-  Argument: ArgumentNode;
-  FragmentSpread: FragmentSpreadNode;
-  InlineFragment: InlineFragmentNode;
-  FragmentDefinition: FragmentDefinitionNode;
-  IntValue: IntValueNode;
-  FloatValue: FloatValueNode;
-  StringValue: StringValueNode;
-  BooleanValue: BooleanValueNode;
-  NullValue: NullValueNode;
-  EnumValue: EnumValueNode;
-  ListValue: ListValueNode;
-  ObjectValue: ObjectValueNode;
-  ObjectField: ObjectFieldNode;
-  Directive: DirectiveNode;
-  NamedType: NamedTypeNode;
-  ListType: ListTypeNode;
-  NonNullType: NonNullTypeNode;
-  SchemaDefinition: SchemaDefinitionNode;
-  OperationTypeDefinition: OperationTypeDefinitionNode;
-  ScalarTypeDefinition: ScalarTypeDefinitionNode;
-  ObjectTypeDefinition: ObjectTypeDefinitionNode;
-  FieldDefinition: FieldDefinitionNode;
-  InputValueDefinition: InputValueDefinitionNode;
-  InterfaceTypeDefinition: InterfaceTypeDefinitionNode;
-  UnionTypeDefinition: UnionTypeDefinitionNode;
-  EnumTypeDefinition: EnumTypeDefinitionNode;
-  EnumValueDefinition: EnumValueDefinitionNode;
-  InputObjectTypeDefinition: InputObjectTypeDefinitionNode;
-  DirectiveDefinition: DirectiveDefinitionNode;
-  SchemaExtension: SchemaExtensionNode;
-  ScalarTypeExtension: ScalarTypeExtensionNode;
-  ObjectTypeExtension: ObjectTypeExtensionNode;
-  InterfaceTypeExtension: InterfaceTypeExtensionNode;
-  UnionTypeExtension: UnionTypeExtensionNode;
-  EnumTypeExtension: EnumTypeExtensionNode;
-  InputObjectTypeExtension: InputObjectTypeExtensionNode;
-}
+export type ASTKindToNode = {
+  [NodeT in ASTNode as NodeT['kind']]: NodeT;
+};
 
 /**
  * @internal
  */
 export const QueryDocumentKeys: {
-  [P in keyof ASTKindToNode]: ReadonlyArray<keyof ASTKindToNode[P]>;
+  [NodeT in ASTNode as NodeT['kind']]: ReadonlyArray<keyof NodeT>;
 } = {
   Name: [],
 
diff --git a/src/language/visitor.ts b/src/language/visitor.ts
index eb018214a4..06ca5aa161 100644
--- a/src/language/visitor.ts
+++ b/src/language/visitor.ts
@@ -1,7 +1,7 @@
 import { inspect } from '../jsutils/inspect';
 import { devAssert } from '../jsutils/devAssert';
 
-import type { ASTNode, ASTKindToNode } from './ast';
+import type { ASTNode } from './ast';
 import { isNode, QueryDocumentKeys } from './ast';
 import { Kind } from './kinds';
 
@@ -12,9 +12,9 @@ import { Kind } from './kinds';
 export type ASTVisitor = EnterLeaveVisitor<ASTNode> | KindVisitor;
 
 type KindVisitor = {
-  readonly [K in keyof ASTKindToNode]?:
-    | ASTVisitFn<ASTKindToNode[K]>
-    | EnterLeaveVisitor<ASTKindToNode[K]>;
+  readonly [NodeT in ASTNode as NodeT['kind']]?:
+    | ASTVisitFn<NodeT>
+    | EnterLeaveVisitor<NodeT>;
 };
 
 interface EnterLeaveVisitor<TVisitedNode extends ASTNode> {
@@ -48,9 +48,9 @@ export type ASTVisitFn<TVisitedNode extends ASTNode> = (
  * another form.
  */
 export type ASTReducer<R> = {
-  readonly [K in keyof ASTKindToNode]?: {
-    readonly enter?: ASTVisitFn<ASTKindToNode[K]>;
-    readonly leave: ASTReducerFn<ASTKindToNode[K], R>;
+  readonly [NodeT in ASTNode as NodeT['kind']]?: {
+    readonly enter?: ASTVisitFn<NodeT>;
+    readonly leave: ASTReducerFn<NodeT, R>;
   };
 };
 
@@ -79,9 +79,11 @@ type ReducedField<T, R> = T extends null | undefined
 
 /**
  * A KeyMap describes each the traversable properties of each kind of node.
+ *
+ * @deprecated Please inline it. Will be removed in v17
  */
 export type ASTVisitorKeyMap = {
-  [P in keyof ASTKindToNode]?: ReadonlyArray<keyof ASTKindToNode[P]>;
+  [NodeT in ASTNode as NodeT['kind']]?: ReadonlyArray<keyof NodeT>;
 };
 
 export const BREAK: unknown = Object.freeze({});
@@ -179,11 +181,7 @@ export function visit(
   visitor: ASTVisitor | ASTReducer<any>,
   visitorKeys: ASTVisitorKeyMap = QueryDocumentKeys,
 ): any {
-  const enterLeaveMap = new Map<
-    keyof ASTKindToNode,
-    EnterLeaveVisitor<ASTNode>
-  >();
-
+  const enterLeaveMap = new Map<Kind, EnterLeaveVisitor<ASTNode>>();
   for (const kind of Object.values(Kind)) {
     enterLeaveMap.set(kind, getEnterLeaveForKind(visitor, kind));
   }
@@ -380,7 +378,7 @@ export function visitInParallel(
  */
 export function getEnterLeaveForKind(
   visitor: ASTVisitor,
-  kind: keyof ASTKindToNode,
+  kind: Kind,
 ): EnterLeaveVisitor<ASTNode> {
   const kindVisitor:
     | ASTVisitFn<ASTNode>
@@ -408,7 +406,7 @@ export function getEnterLeaveForKind(
 // istanbul ignore next (Deprecated code)
 export function getVisitFn(
   visitor: ASTVisitor,
-  kind: keyof ASTKindToNode,
+  kind: Kind,
   isLeaving: boolean,
 ): ASTVisitFn<ASTNode> | undefined {
   const { enter, leave } = getEnterLeaveForKind(visitor, kind);