Re: Function Reference Issues

A “top-level” reference should not contain things with unbound type
variables (in a module declaration).

let my_func   obj  = assert false
has type  'a -> 'b   (→ 2 type variables)

If you want that reference you should force a "final" type, like:

let my_func_ref : (int -> unit) ref = ref my_func






On Thu, Jun 25, 2015 at 12:12 PM, Kenneth Miller
[email protected] [ocaml_beginners]
<[email protected]> wrote:
>
>
> I have some let definitions binding some functions to function references.
> This works nicely, but the typing system is giving me some hell about "type
> variables that cannot be generalized"; in my edits to the to promote the
> list type to a Core list, I have to provide type parameters the module
> constructors. This works fine so far, but now I have to have a declared
> reference that can be updated; it seems that I can't declare it raw,
> however:
>
> let my_func   obj  = assert false
>
>
> ...
>
> let my_func    = ref my_func
>
> At the rebinding, let my_func becomes a type issue with:
>
> Error: The type of this expression, (<type> -> <type>) ref,
>        contains type variables that cannot be generalized
>
> I don't know how to just get the compiler to accept that my_func is a
> function reference, and to allow it's declaration. Literally I can't do
> anything regarding just adding a () parameter, because then I'm not binding
> a value, I'm binding the function that returns a reference; you can't update
> that, because the function reference returned in each of the implementing
> modules that edit these such references is local to that executing
> scope-it's not the reference instance we want.
>
> How can I either get the compiler to accept such a function reference?
>
>
>
>