Re: Recursive Variants of Set

Thanks Gabriel for saving me again :-)

Also, I was a bit silly. In my haste, I also forgot to use List.fold_right.
After reading Set's documentation carefully again, I realized I have to
use: Id (IdSet.add (Common "C") IdSet.empty).

Thank you so much,
==============================
Jacques du Preez

Web: OpenLandscape.net
EMail: [email protected]
Twitter: @jacquesdp


On Mon, Jul 14, 2014 at 5:25 PM, Gabriel Scherer [email protected]
[ocaml_beginners] <[email protected]> wrote:

>
>
> As the variant constructors Common and ObjStore are declared in the
> Identity sub-module, you should access them as Identity.Common and
> Identity.ObjStore:
>
> # IdSet.elements
>   (List.fold_right IdSet.add
>      [Identity.Common "C"; Identity.ObjStore "OS"]
>      IdSet.empty);;
> - : IdSet.elt list = [Identity.Common "C"; Identity.ObjStore "OS"]
>
> It is also possible to "open" the Identity module to put its names in
> scope so that you don't have to prefix them. You can also (in recent-ish
> versions of OCaml) open a module locally using the syntaxes (let open
> <module> in <expression>) or (<module>.(<expression>)), for example:
>
> IdSet.elements
>   (List.fold_right IdSet.add
>      Identity.([Common "C"; ObjStore "OS"])
>      IdSet.empty);;
>
>
>
>
> On Mon, Jul 14, 2014 at 4:51 PM, Jacques du Preez [email protected]
> [ocaml_beginners] <[email protected]> wrote:
>
>>
>>
>> Hi,
>>
>> Okay, so I got the recursive module right, and a variant that's a set of
>> the variant type itself - Id of IdSet.t:
>>
>> module rec Identity :
>> sig
>>   type id = | Id of IdSet.t
>>     | Common of string
>>     | ObjStore of string
>> end
>> = struct
>>   type id = | Id of IdSet.t
>>     | Common of string
>>     | ObjStore of string
>> end
>> and IdSet: Set.S with type elt = Identity.id
>>  = Set.Make(
>>        struct
>>  type t = Identity.id
>>  let compare = Pervasives.compare
>>        end)
>>
>> But for the life of me I can seem to use the "Id" variant type. How on
>> earth do I create "Id" with a set of type id's other variances?
>>
>> In other words, if I wanted to use the variant Common for instance, I'll
>> say: Common "some str value". How do I do this for Id, as in something
>> like:
>>     Id IdSet.add ([Common "C"; ObjStore "OS"] IdSet.empty)
>>
>> However, I've tried numerous variations of the above statement, and it's
>> either complaining about a syntax error, or that type Common.Identity.id
>> doesn't have a constructor - depending on where I place the parenthesis.
>>
>> Help!?
>>
>> Thank you,
>> ==============================
>> Jacques du Preez
>>
>> Web: OpenLandscape.net
>> EMail: [email protected]
>> Twitter: @jacquesdp
>>
>>
>> On Sat, Jul 12, 2014 at 5:25 PM, Jacques du Preez <[email protected]>
>> wrote:
>>
>>> Thank you so much Gabriel. I'll have a look at that. Thanks!
>>>
>>> ==============================
>>> Jacques du Preez
>>>
>>> Web: OpenLandscape.net
>>> EMail: [email protected]
>>> Twitter: @jacquesdp
>>>
>>>
>>> On Sat, Jul 12, 2014 at 5:20 PM, Gabriel Scherer
>>> [email protected] [ocaml_beginners] <
>>> [email protected]> wrote:
>>>
>>>>
>>>>
>>>> It is not correct to use the name of a compilation unit (.ml{,i} files)
>>>> from within its own code: the cause of the circular dependency error here
>>>> is the use of paths of the form Common.foo.
>>>>
>>>> To recursively define a type and sets over it, you should use recursive
>>>> modules. This is actually the example given in the manual for recursive
>>>> modules:
>>>>   http://caml.inria.fr/pub/docs/manual-ocaml/extn.html#sec220
>>>>
>>>>
>>>> On Sat, Jul 12, 2014 at 5:13 PM, Jacques du Preez [email protected]
>>>> [ocaml_beginners] <[email protected]> wrote:
>>>>
>>>>>
>>>>>
>>>>> Hi,
>>>>>
>>>>> Please consider my common.mli:
>>>>>
>>>>> type id = | Id of Common.Id_set.t
>>>>>           | Common of string
>>>>>   | ObjStore of string
>>>>>
>>>>> module Id_set : (Set.S with type elt = id)
>>>>>
>>>>> Now my common.ml:
>>>>>
>>>>> type id = | Id of Common.Id_set.t
>>>>>           | Common of string
>>>>>   | ObjStore of string
>>>>>
>>>>> module Id_set = Set.Make(
>>>>>     struct
>>>>>       type t = id
>>>>>       let compare = Pervasives.compare
>>>>>     end)
>>>>>
>>>>> The above gives an circular build error. If I change Common.Id_set.t
>>>>> to Id_set.t, then I get an unbound module error - I'm assuming this is
>>>>> because the Id_set module declaration is after the variant declaration.
>>>>>
>>>>> What I'd like to know is, how would I change my Id variant to be of
>>>>> type "id set"? Is this possible? The problem here is that Id_set depends on
>>>>> variant id, and vice versa. How to solve this?
>>>>>
>>>>> Thanks,
>>>>>
>>>>> ==============================
>>>>> Jacques du Preez
>>>>>
>>>>> Web: OpenLandscape.net
>>>>> Twitter: @jacquesdp
>>>>>
>>>>>
>>>>>
>>>>
>>>
>>
>>
>>
>  
>