Hi all,

On Wed, 28 Sep 2011, Jacques Garrigue wrote:

> On 2011/09/28, at 5:22, Walter Cazzola wrote:
>
>> I still have one problem: how can I assign to a the type 'a list? by
>> using «type a= 'a list» I get
>>
>>  Error: Unbound type parameter 'a
>
> Same thing: you need to make explicit the contents of the list.
> So this can be type a = int list.
> On the other hand if you are trying to refine the signature, you
> can also write
>  type t
>  type a = t list
> keeping t abstract.

thanks for the explanation but I'm still unable to match the 2 types (I
have attached the code again). I get this message:
     # module M0 = Continuation(StringConcat);;
     Error: Signature mismatch:
            Modules do not match:
              sig
                type t = StringConcat.t
                type a = t list
                and b = t
                and c = t list
                val op : 'a -> 'a list -> 'a list
                val init : 'a list
              end
            is not included in
              OpVarADT.OpVarADT
            Values do not match:
              val op : 'a -> 'a list -> 'a list
            is not included in
              val op : a -> b -> c

I have also tried to set the abstract type t to string butwithout any
luck.

     # module M0 = Continuation(StringConcat with StringConcat.t = string) ;;
     Error: Syntax error

I feel myself quite dumb but I can't figure out how to fix it.

Walter

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