Seq.sortWithStable is stable

dotnet · Jul 29, 2015 · 3c9e689 · 3c9e689
1 parent 2149c2d
commit 3c9e689
Showing 1 changed file with 10 additions and 0 deletions.
diff --git a/src/fsharp/FSharp.Core.PropertyTests/SeqProperties.fs b/src/fsharp/FSharp.Core.PropertyTests/SeqProperties.fs
@@ -19,6 +19,16 @@ let sortByStable<'a when 'a : comparison> (xs : 'a []) =
 let ``Seq.sortBy is stable`` () =
     Check.QuickThrowOnFailure sortByStable<int>
     Check.QuickThrowOnFailure sortByStable<string>
+
+let sortWithStable<'a when 'a : comparison> (xs : 'a []) =
+    let indexed = xs |> Seq.indexed |> Seq.toList
+    let sorted = indexed |> Seq.sortWith (fun x y -> compare (snd x) (snd y))
+    isStable sorted
+
+[<Test>]
+let ``Seq.sortWithStable is stable`` () =
+    Check.QuickThrowOnFailure sortWithStable<int>
+    Check.QuickThrowOnFailure sortWithStable<string>
 
 let distinctByStable<'a when 'a : comparison> (xs : 'a []) =
     let indexed = xs |> Seq.indexed