Introduce AsReadOnlyList extension to cast arrays

csharp/Lib/Utils/ArrayExtensions.cs

@@ -13,4 +13,6 @@ public static class ArrayExtensions
         Array.Fill(ts, element);
         return ts;
     }
+
+    public static IReadOnlyList<T> AsReadOnlyList<T>(this T[] ts) => ts;
 }

csharp/Lib/Utils/EnumerableUtils.cs

@@ -277,6 +277,9 @@ public static class EnumerableUtils
 
     public static T[] ToArray<T>(this IEnumerable<T> ts, Int32 n)
     {
+        if (ts is T[] ta)
+            return ta;
+        
         var array = new T[n];
         var i = 0;
 
@@ -296,6 +299,8 @@ public static class EnumerableUtils
         return ts as T[] ?? ts.ToArray(ts.Count);
     }
 
+  
+    
     public static IEnumerable<T> Concat<T>(this IEnumerable<T> ts, T last)
     {
         foreach (var t in ts)