Fix for Issue 533 - Stack overflow error after using Sequence to get …

…from IEnumerable<Option<T>> to Option<IEnumerable<T>> #533
louthy · Dec 7, 2018 · c808fb7 · c808fb7
1 parent 5bf2bae
commit c808fb7
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Showing 2 changed files with 21 additions and 5 deletions.
diff --git a/LanguageExt.Core/ClassInstances/Monad/MEnumerable.cs b/LanguageExt.Core/ClassInstances/Monad/MEnumerable.cs
@@ -87,11 +87,8 @@ public Func<Unit, S> FoldBack<S>(IEnumerable<A> fa, S state, Func<S, A, S> f) =>
             fa.FoldBack(state, f);
 
         [Pure]
-        public IEnumerable<A> Plus(IEnumerable<A> ma, IEnumerable<A> mb)
-        {
-            foreach (var a in ma) yield return a;
-            foreach (var b in mb) yield return b;
-        }
+        public IEnumerable<A> Plus(IEnumerable<A> ma, IEnumerable<A> mb) =>
+            Enumerable.Concat(ma, mb);
 
         [Pure]
         public IEnumerable<A> Zero() =>

diff --git a/LanguageExt.Tests/IssuesTests.cs b/LanguageExt.Tests/IssuesTests.cs
@@ -481,4 +481,23 @@ public static async Task<Option<int>> Calculate(int x, int y, int z)
         //                    .IfLeft(0);
         //}
     }
+
+    public class Issue533
+    {
+        [Fact]
+        public void Test()
+        {
+
+            var someData = Enumerable
+                .Range(0, 30000)
+                .Select(_ => Guid.NewGuid().ToString())
+                .ToArray();
+
+            var result = someData
+                .Select(Some)
+                .Sequence()
+                .Map(x => x.ToArray());
+        }
+
+    }
 }