Implement 'Collection.first_position(of:)'

hylo-lang · Aug 5, 2024 · d4eacda · d4eacda
1 parent 9338c0e
commit d4eacda
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diff --git 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
@@ -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() {