[Caml-list] Mutually recursive closures?

[Anthony Tavener <anthony.tavener@gmail.com>]

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I was considering returning a couple of closures to help organize my UI
code, essentially representing current UI mode by one of these closures. But
then I run into a problem because the types are infinite (returns a
function, which returns a function, ...)

A simplified example:

# let rec a () = printf "state a\n"; b
       and b () = printf "state b\n"; a

Error: This expression has type unit -> unit -> 'a
       but an expression was expected of type 'a


Is there a way I can do this? To express (or 'hide') the cyclic nature of
the type resolution?

I've considered using continuations, but that seems heavy-weight for what
I'm looking to do. And as far as I can tell I'd need to leverage Oleg's
delimcc (which I'd love to start using and wrap my head around -- but for a
task worthy of it!).

I can use a variant to represent states/modes and have a dispatcher which
runs the right code... but this introduces what feels like an unnecessary
layer of distraction. Returning the closure of the "next state" seems
straightforward, but introduces cycles into the typing. :(

I'm hoping I'm missing something simple. Thank-you for any assistance!

 -Tony

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