On 5/17/12 7:43 PM, Yitzhak Mandelbaum wrote:
> Thanks to everyone who responded.  FWIW, I found the argument in favor of options most compelling as a general approach.
> 
> Yitzhak
> 

Note that there is a drawback to that approach: loss of polymorphism.

# let mmap = Some List.map;;
val mmap : (('a -> 'b) -> 'a list -> 'b list) option = Some <fun>

# let mmap2 = match mmap with | None -> failwith "Nope" | Some x -> x;;
val mmap2 : ('_a -> '_b) -> '_a list -> '_b list = <fun>

I suspect that first-class modules can help here, but I have not really
had time to toy with them yet.

Cheers,
 David