[Caml-list] Closure & Ref

["chris.danx" <chris.danx@ntlworld.com>]

Hi,

I was toying with ocaml just now and have successfully written a 
function that takes and int that produces a function that takes an int 
to add to the original.

let prodAdd x =
    let value = ref x in
       fun y -> !value + y;;

Now I want to do a function that takes a ref to a list and returns a 
function that adds items to the list and produce a function that returns 
another that returns the list.  How do I do that?

let prod_list_acc a =
   fun x -> a := x :: !a; true;;

let return_acc a =
   fun () -> !a;;

but that gives a "unit -> int list" =.  How do you get a copy of the 
list values?


This might seem like a crazy thing to do but I am toying with an idea 
relating to a paper I read on traits.  Instead of having classes at all 
you can just have traits, closures and mutable values.


Cheers,
Chris

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