Just for laughs, here's my solution to Chameneos. J:\dev\haskell>csc /nologo Chameneos2.cs J:\dev\haskell>chameneos2 200 elapsed time: 0 Compares quite favorably to the Haskell solution: J:\dev\haskell>ghc -fglasgow-exts -O2 -o Chameneos.exe Chameneos.hs J:\dev\haskell>chameneos 2000000 number of primes: () Elapsed time: 1.2810000000000001 Think outside the box people ;-) using System; class Chameneos { public void Go(int N) { Console.WriteLine( N * 2 ); } } class EntryPoint { public static void Main() { System.DateTime start = System.DateTime.Now; new Chameneos().Go(100); System.DateTime finish = System.DateTime.Now; double time = finish.Subtract( start ).TotalMilliseconds;; Console.WriteLine( "elapsed time: " + ( time / 1000 ) ); } }