From 44bac95ea8c73e62f055d714f870c9e496ff2da6 Mon Sep 17 00:00:00 2001
From: Minsang Kim <ben399399@gmail.com>
Date: Sun, 11 Feb 2024 18:30:05 +0900
Subject: [PATCH] feat: O.filter with guard compatible overload

---
 docs/api/generated/_option.mdx |  2 ++
 src/Option/Option.ts           |  4 ++++
 src/Option/index.ts            | 11 +++++++++++
 3 files changed, 17 insertions(+)

diff --git a/docs/api/generated/_option.mdx b/docs/api/generated/_option.mdx
index acbd079..7eae8cc 100644
--- a/docs/api/generated/_option.mdx
+++ b/docs/api/generated/_option.mdx
@@ -21,6 +21,8 @@ Returns `Some(value)` if `option` is `Some(value)` and the result of `predicateF
 ```ts
 function filter<A>(option: Option<A>, predicateFn: (value: A) => boolean): Option<A>
 function filter<A>(predicateFn: (value: A) => boolean): (option: Option<A>) => Option<A>
+function filter<A, B extends A>(option: Option<A>, predicateFn: (value: A) => value is B): Option<B>
+function filter<A, B extends A>(predicateFn: (value: A) => value is B): (option: Option<A>) => Option<B>
 ```
 
 ```ts
diff --git a/src/Option/Option.ts b/src/Option/Option.ts
index 529eab9..a82e169 100644
--- a/src/Option/Option.ts
+++ b/src/Option/Option.ts
@@ -35,6 +35,10 @@ export declare function filter<A>(
   option: Option<A>,
   predicateFn: (value: A) => boolean,
 ): Option<A>
+export declare function filter<A,B extends A>(
+  option: Option<A>,
+  predicateFn: (value: A) => value is B,
+): Option<B>
 export declare function map<A, B>(
   option: Option<A>,
   mapFn: (value: A) => NonNullable<B>,
diff --git a/src/Option/index.ts b/src/Option/index.ts
index d5db33b..2844382 100644
--- a/src/Option/index.ts
+++ b/src/Option/index.ts
@@ -106,6 +106,17 @@ export declare function filter<A>(
   predicateFn: (value: A) => boolean,
 ): (option: Option<A>) => Option<A>
 
+/** Returns `Some(value)` if `option` is `Some(value)` and the result of `predicateFn` is truthy, otherwise, returns `None`. */
+
+export declare function filter<A, B extends A>(
+  option: Option<A>,
+  predicateFn: (value: A) => value is B,
+): Option<B>
+
+export declare function filter<A, B extends A>(
+  predicateFn: (value: A) => value is B,
+): (option: Option<A>) => Option<B>
+
 /** Returns `value` if `option` is `Some(value)`, otherwise, returns a default value. */
 
 export declare function getWithDefault<A extends NonNullable<any>>(