From d62fbf04fec0cbe7f9bdae70555c342430c3da00 Mon Sep 17 00:00:00 2001
From: Tetsuharu OHZEKI <saneyuki.snyk@gmail.com>
Date: Mon, 12 Sep 2016 13:06:01 +0900
Subject: [PATCH] feat(filter): Observable<T>.filter() can take type guard as
 the predicate function

---
 src/operator/filter.ts | 1 +
 1 file changed, 1 insertion(+)

diff --git a/src/operator/filter.ts b/src/operator/filter.ts
index 980a91b380..7a4958926c 100644
--- a/src/operator/filter.ts
+++ b/src/operator/filter.ts
@@ -50,6 +50,7 @@ export function filter<T>(predicate: (value: T, index: number) => boolean,
 
 export interface FilterSignature<T> {
   (predicate: (value: T, index: number) => boolean, thisArg?: any): Observable<T>;
+  <S extends T>(predicate: (value: T, index: number) => value is S, thisArg?: any): Observable<S>;
 }
 
 class FilterOperator<T> implements Operator<T, T> {