Proposal: give Ptr a nominal role

[Daniel Cartwright]

i agree with carter regarding the Storable-Ptr relationship. It seems to me
that Storable is tied to Ptr. Some concrete evidence of this is in the
Data.Primitive.Ptr API

On Thu, Nov 1, 2018 at 2:26 PM Carter Schonwald <carter.schonwald at gmail.com>
wrote:

> phrased differnetly: storable provides one (c compatible) isomorphism
> between fixed size values in haskell and c
>
> the moment you want to talk about something that isn't fixed sized, like a
> unicode character (which is a sequence of one or more code points, which we
> call Char in haskell), storable doesn't apply.
>
> On Thu, Nov 1, 2018 at 2:23 PM Carter Schonwald <
> carter.schonwald at gmail.com> wrote:
>
>> ... Ptr *is not* tied to storable, Storable is a convenience for FFI
>> integration .. storable is tied to ptr
>>
>> there are whole MOUNTAINS of haskell code that underly this, and we can't
>> lawyer it away with some opinions
>>
>> On Thu, Nov 1, 2018 at 2:16 PM David Feuer <david.feuer at gmail.com> wrote:
>>
>>> Indeed. I think the point is that Ptr should be thought of as tied to
>>> Storable. If you want to use an Addr# for something else, then you
>>> shouldn't be using Ptr!
>>>
>>> On Thu, Nov 1, 2018, 2:13 PM Evan Laforge <qdunkan at gmail.com wrote:
>>>
>>>> On Thu, Nov 1, 2018 at 10:47 AM Carter Schonwald
>>>> <carter.schonwald at gmail.com> wrote:
>>>> > a good example might be Ptr Char.  Is this a single location of a
>>>> 32bit / utf32 code point, or an array of utf8 code points or utf32 code
>>>> points?
>>>> > is it null terminated vs there being an extra sequence length? These
>>>> are all valid things that can be happening. And
>>>>
>>>> I'm not sure if it affects your point, but I sure hope a 'Ptr Char'
>>>> points to a 4 byte haskell Char as it claims, and 'Ptr CChar' points
>>>> to a 1 byte C char, as it claims.  Otherwise, sizeOf will be wrong and
>>>> array indexing will go out of bounds.
>>>>
>>>> Of course, in the C case, whether or not there are further chars after
>>>> that and if they are terminated and what is the encoding is all
>>>> ambiguous, as it always is for C.
>>>> _______________________________________________
>>>> Libraries mailing list
>>>> Libraries at haskell.org
>>>> http://mail.haskell.org/cgi-bin/mailman/listinfo/libraries
>>>>
>>> _______________________________________________
> Libraries mailing list
> Libraries at haskell.org
> http://mail.haskell.org/cgi-bin/mailman/listinfo/libraries
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mail.haskell.org/pipermail/libraries/attachments/20181101/9c156f13/attachment.html>