From d4eacda41ca790dd7a93ab17ea108a0e40808ce9 Mon Sep 17 00:00:00 2001
From: Dimi Racordon <dimitri.racordon@gmail.com>
Date: Mon, 5 Aug 2024 11:55:37 +0200
Subject: [PATCH] Implement 'Collection.first_position(of:)'

---
 StandardLibrary/Sources/Core/Collection.hylo      | 12 ++++++++++++
 Tests/LibraryTests/TestCases/CollectionTests.hylo |  1 +
 2 files changed, 13 insertions(+)

diff --git a/StandardLibrary/Sources/Core/Collection.hylo b/StandardLibrary/Sources/Core/Collection.hylo
index 11c6a243b..d7d9ba30d 100644
--- a/StandardLibrary/Sources/Core/Collection.hylo
+++ b/StandardLibrary/Sources/Core/Collection.hylo
@@ -85,3 +85,15 @@ public extension Collection {
   }
 
 }
+
+public extension Collection where Element: Equatable {
+
+  /// Returns the position of the first element of `self` that is equal to `needle`, or
+  /// `end_position()` if no such element exists.
+  ///
+  /// - Complexity: O(n), where n is the number of elements in `self`.
+  public fun first_position(of needle: Element) -> Position {
+    first_position(where: fun (_ e) { e == needle })
+  }
+
+}
diff --git a/Tests/LibraryTests/TestCases/CollectionTests.hylo b/Tests/LibraryTests/TestCases/CollectionTests.hylo
index 4c8b97f3c..0b24a76e2 100644
--- a/Tests/LibraryTests/TestCases/CollectionTests.hylo
+++ b/Tests/LibraryTests/TestCases/CollectionTests.hylo
@@ -21,6 +21,7 @@ fun test_count() {
 fun test_first_position() {
   let a = 4
   precondition(a.first_position(where: fun (_ x) { x.copy() }) == 2)
+  precondition(a.first_position(of: true) == 2)
 }
 
 fun test_reduce() {