Sync subscription TS defintions with Flow

tstypes/subscription/asyncIteratorReject.d.ts

@@ -0,0 +1,6 @@
+/**
+ * Given an error, returns an AsyncIterable which will fail with that error.
+ *
+ * Similar to Promise.reject(error)
+ */
+export default function asyncIteratorReject(error: Error): AsyncIterator<void>;

tstypes/subscription/index.d.ts

@@ -1 +1,5 @@
-export { subscribe, createSourceEventStream } from './subscribe';
+export {
+  subscribe,
+  createSourceEventStream,
+  SubscriptionArgs,
+} from './subscribe';

tstypes/subscription/mapAsyncIterator.d.ts

@@ -0,0 +1,9 @@
+/**
+ * Given an AsyncIterable and a callback function, return an AsyncIterator
+ * which produces values mapped via calling the callback function.
+ */
+export default function mapAsyncIterator<T, U>(
+  iterable: AsyncIterable<T>,
+  callback: (arg: T) => PromiseOrValue<U>,
+  rejectCallback?: (arg: any) => PromiseOrValue<U>,
+): AsyncGenerator<U, void, void>;

tstypes/subscription/subscribe.d.ts

@@ -1,11 +1,22 @@
 import Maybe from '../tsutils/Maybe';
-import { GraphQLSchema } from '../type/schema';
 import { DocumentNode } from '../language/ast';
-import { GraphQLFieldResolver } from '../type/definition';
 import {
   ExecutionResult,
   ExecutionResultDataDefault,
 } from '../execution/execute';
+import { GraphQLSchema } from '../type/schema';
+import { GraphQLFieldResolver } from '../type/definition';
+
+export interface SubscriptionArgs {
+  schema: GraphQLSchema;
+  document: DocumentNode;
+  rootValue?: any;
+  contextValue?: any;
+  variableValues?: Maybe<Record<string, any>>;
+  operationName?: Maybe<string>;
+  fieldResolver?: Maybe<GraphQLFieldResolver<any, any>>;
+  subscribeFieldResolver?: Maybe<GraphQLFieldResolver<any, any>>;
+}
 
 /**
  * Implements the "Subscribe" algorithm described in the GraphQL specification.
@@ -27,16 +38,9 @@ import {
  *
  * Accepts either an object with named arguments, or individual arguments.
  */
-export function subscribe<TData = ExecutionResultDataDefault>(args: {
-  schema: GraphQLSchema;
-  document: DocumentNode;
-  rootValue?: any;
-  contextValue?: any;
-  variableValues?: Maybe<{ [key: string]: any }>;
-  operationName?: Maybe<string>;
-  fieldResolver?: Maybe<GraphQLFieldResolver<any, any>>;
-  subscribeFieldResolver?: Maybe<GraphQLFieldResolver<any, any>>;
-}): Promise<
+export function subscribe<TData = ExecutionResultDataDefault>(
+  args: SubscriptionArgs,
+): Promise<
   AsyncIterableIterator<ExecutionResult<TData>> | ExecutionResult<TData>
 >;