Right. what confuses me is, how the format type has 'a -> 'b instead of 'a.
Your wrapper returns a function. Type ‘a, the argument to that function, is determined by the first %-conversion in the format string. The function returns type ‘b. If your format argument has one %-conversion, type ‘b will be a string. If it has more than one, type ‘b will be a function accepting the remaining arguments.
# let g = f “%d %d”;;
val g : int -> int -> string = <fun>
# let h = g 0;;
val h : int -> string = <fun>
# h 1;;
- : string = "0 1"
In the past partial application of printf family functions hasn’t worked well, so test before relying on behavior of the returned function.
> On Feb 9, 2015, at 06:58 , Jiten Pathy <jpathy@fssrv.net> wrote:
>
> When i define a wrapper around format functions like
>
> let f s = (fun x -> Printf.sprintf s x);;
>
> val f : ('a -> 'b, unit, bytes) format -> 'a -> 'b = <fun>
>
> I am confused about the inferred type. where does this 'b comes from?
>
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