From 4cad768b0ceeff1dc739ca716eae19d93f6c1a8d Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Vincent=20Fran=C3=A7ois?= <vincent.francois@inato.com>
Date: Mon, 16 Sep 2024 18:45:55 +0200
Subject: [PATCH] feat: add HashMap.HashMap.Entry utility type (#3618)

---
 .changeset/chilled-hotels-sniff.md |  5 +++++
 packages/effect/dtslint/HashMap.ts | 10 +++++++++-
 packages/effect/src/HashMap.ts     | 16 ++++++++++++++++
 3 files changed, 30 insertions(+), 1 deletion(-)
 create mode 100644 .changeset/chilled-hotels-sniff.md

diff --git a/.changeset/chilled-hotels-sniff.md b/.changeset/chilled-hotels-sniff.md
new file mode 100644
index 0000000000..8aa434d4b6
--- /dev/null
+++ b/.changeset/chilled-hotels-sniff.md
@@ -0,0 +1,5 @@
+---
+"effect": minor
+---
+
+Adds HashMap.HashMap.Entry type helper
diff --git a/packages/effect/dtslint/HashMap.ts b/packages/effect/dtslint/HashMap.ts
index 00ed98ce10..ed8c53bc8d 100644
--- a/packages/effect/dtslint/HashMap.ts
+++ b/packages/effect/dtslint/HashMap.ts
@@ -1,6 +1,7 @@
-import { pipe } from "effect/Function"
+import { hole, pipe } from "effect/Function"
 import * as HashMap from "effect/HashMap"
 import * as Predicate from "effect/Predicate"
+import type * as Types from "effect/Types"
 
 declare const hmLiterals: HashMap.HashMap<"k", "v">
 declare const numbers: HashMap.HashMap<string, number>
@@ -23,6 +24,13 @@ export type K = HashMap.HashMap.Key<typeof hmLiterals>
 // $ExpectType "v"
 export type V = HashMap.HashMap.Value<typeof hmLiterals>
 
+// -------------------------------------------------------------------------------------
+// HashMap.Entry
+// -------------------------------------------------------------------------------------
+
+// $ExpectType ["k", "v"]
+hole<Types.Simplify<HashMap.HashMap.Entry<typeof hmLiterals>>>()
+
 // -------------------------------------------------------------------------------------
 // filter
 // -------------------------------------------------------------------------------------
diff --git a/packages/effect/src/HashMap.ts b/packages/effect/src/HashMap.ts
index 47f3597112..f5a881f727 100644
--- a/packages/effect/src/HashMap.ts
+++ b/packages/effect/src/HashMap.ts
@@ -66,6 +66,22 @@ export declare namespace HashMap {
    * @category type-level
    */
   export type Value<T extends HashMap<any, any>> = [T] extends [HashMap<infer _K, infer _V>] ? _V : never
+
+  /**
+   * This type-level utility extracts the entry type `[K, V]` from a `HashMap<K, V>` type.
+   *
+   * @example
+   * import { HashMap } from "effect"
+   *
+   * declare const hm: HashMap.HashMap<string, number>
+   *
+   * // $ExpectType [string, number]
+   * type V = HashMap.HashMap.Entry<typeof hm>
+   *
+   * @since 3.9.0
+   * @category type-level
+   */
+  export type Entry<T extends HashMap<any, any>> = [Key<T>, Value<T>]
 }
 
 /**