Hidden Features of F#

Answer 1

There are no hidden features, because F# is in design mode. All what we have is a Technical Preview, which changes every two month.

see http://research.microsoft.com/fsharp/

Answer 2

See this question

F# operator "?"

for info on the question-mark operator and how it provides the basic language mechanism to build a feature akin to 'dynamic' in C#.

Answer 3

Yes, F# doesn't have any 'hidden' features, but it sure does have a lot of power packed into the simple language. A less-known feature of the language, is where you can basically enable duck typing despite the fact F# is staticaly typed.

Answer 4

Use of F# as a utility scripting language may be under appreciated. F# enthusiasts tend to be quants. Sometimes you want something to back up your MP3s (or dozens of database servers) that's a little more robust than batch. I've been hunting for a modern replacement for jscript / vbscript. Lately, I've used IronPython, but F# may be more complete and the .NET interaction is less cumbersome.

I like curried functions for entertainment value. Show a curried function to a pure procedural / OOP program for at least three WTFs. Starting with this is a bad way to get F# converts, though :)

Answer 5

Inlined operators on generic types can have different generic constraints:

type 'a Wrapper = Wrapper of 'a with
  static member inline (+)(Wrapper(a),Wrapper(b)) = Wrapper(a + b)
  static member inline Exp(Wrapper(a)) = Wrapper(exp a)

let objWrapper = Wrapper(obj())
let intWrapper = (Wrapper 1) + (Wrapper 2)
let fltWrapper = exp (Wrapper 1.0)

(* won''t compile *)
let _ = exp (Wrapper 1)