F# case insensitive string compare

Also, you can use F# type extensions mechanics:

> type System.String with
-   member s1.icompare(s2: string) =
-     System.String.Equals(s1, s2, System.StringComparison.CurrentCultureIgnoreCase);;
> "test".icompare "tEst";;
val it : bool = true

How about writing an extension method to make this shorter.