[Haskell-cafe] Lazy series [was : Preventing sharing]

[Tom Ellis]

On Sat, Jan 09, 2016 at 07:48:04PM +0100, Arjen wrote:
> >I'm not quite sure what you're asking, but consider the difference between
> >these two calls to the function id in OCaml.
> >
> ># let id x = x;;
> >val id : 'a -> 'a = <fun>
> >
> ># id (Printf.printf "Hello");;
> >Hello- : unit = ()
> >
> ># id (fun () -> Printf.printf "Hello");;
> >- : unit -> unit = <fun>
> >
> >
> >The correspond to the following in an imaginary impure Haskell-like
> >language:
> >
> >id (print "Hello")
> >"Hello"
> >
> >id (\() -> print "Hello")
> ><no output>
> 
> I think I see what you mean. Then in OCaml exps would have type
> unit->Int? And to get the value, you would use exps ()?

In OCaml exps could have type A, where A is isomorphic to

    () -> (Double, A)

To get the first value you could (effectively) use 'exps ()'.  You get a
tail of type A along with it.  I suggest you look through Oleg's code.  It's
quite illuminating.

    http://okmij.org/ftp/ML/powser.ml

Tom