"Kevin Quick" writes:
> I was trying to put them on the inside. Essentially I was trying to
> use the 'a' portion of the LNode as a type that would provide methods
> from which I could reconstruct the shape of the Graph. Or to put it
> another way, I had a collection of data and I wanted to be a
On Sat, 01 May 2010 15:42:09 -0700, Ivan Lazar Miljenovic
wrote:
instance Graph GrB where
-- instance (Cls a) => Graph GrB where -- error: ambiguous constraint, must
mention type a
-- instance (Cls a) => forall a. Graph GrB where -- error: malformed instance
header
-- instance (Cls a) Graph
"Kevin Quick" writes:
> Yes, I was hoping to use FGL directly (or it's replacement as I've
> scanned some of the recent Cafe discussions and seen that Ivan in
> particular is undertaking this).
FGL isn't really set up for this kind of "the data type _must_ be
restricted" approach.
> The key here
On Sat, 01 May 2010 01:01:47 -0700, Sebastian Fischer
wrote:
On May 1, 2010, at 8:08 AM, Ivan Lazar Miljenovic wrote:
* I can't redefine the Graph methods to introduce the (Cls a)
constraint [reasonable]
Not sure if you can.
I think Kevin means that he cannot change the signature of the
On Fri, 30 Apr 2010 23:30:21 -0700, Jason Dagit wrote:
On Fri, Apr 30, 2010 at 11:08 PM, Ivan Lazar Miljenovic <
ivan.miljeno...@gmail.com> wrote:
You're putting the constraint in the wrong places: put the "(Cls a) => "
in the actual functions where you need it.
I need to use Cls methods in
Jason Dagit writes:
> On Sat, May 1, 2010 at 12:49 AM, Ivan Lazar Miljenovic <
> I thought we were discussing how expressive the Graph typeclass is, not
> whether I made a sensible implementation. I mean, I could pretty easily fix
> that "problem", but I think that's not the important topic. Fo
Sebastian Fischer writes:
>> Furthermore, as I said earlier,
>> it doesn't make sense to constrain the label type just to make an
>> instance of a type class.
>>
>> (Now, if we had other functions in there which _might_ depend on the
>> label types, this _would_ make sense; as it stands however,
On Sat, May 1, 2010 at 12:49 AM, Ivan Lazar Miljenovic <
ivan.miljeno...@gmail.com> wrote:
> Jason Dagit writes:
>
> > On Sat, May 1, 2010 at 12:23 AM, Ivan Lazar Miljenovic <
> > ivan.miljeno...@gmail.com> wrote:
> >
> >> Hmmm this is an interesting way of doing it, but I would argue that
>
On May 1, 2010, at 8:08 AM, Ivan Lazar Miljenovic wrote:
* I can't redefine the Graph methods to introduce the (Cls a)
constraint [reasonable]
Not sure if you can.
I think Kevin means that he cannot change the signature of the methods
in the Graph class because those are defined in the FG
Furthermore, as I said earlier,
it doesn't make sense to constrain the label type just to make an
instance of a type class.
(Now, if we had other functions in there which _might_ depend on the
label types, this _would_ make sense; as it stands however, it
doesn't.)
You'll notice that my empty
Jason Dagit writes:
> On Sat, May 1, 2010 at 12:23 AM, Ivan Lazar Miljenovic <
> ivan.miljeno...@gmail.com> wrote:
>
>> Hmmm this is an interesting way of doing it, but I would argue that
>> it's pointless: the fact that you're using MPTCs doesn't give you
>> anything extra that the original
On Sat, May 1, 2010 at 12:23 AM, Ivan Lazar Miljenovic <
ivan.miljeno...@gmail.com> wrote:
> Hmmm this is an interesting way of doing it, but I would argue that
> it's pointless: the fact that you're using MPTCs doesn't give you
> anything extra that the original class. Furthermore, as I said
Hmmm this is an interesting way of doing it, but I would argue that
it's pointless: the fact that you're using MPTCs doesn't give you
anything extra that the original class. Furthermore, as I said earlier,
it doesn't make sense to constrain the label type just to make an
instance of a type cla
On Fri, Apr 30, 2010 at 11:53 PM, Ivan Lazar Miljenovic <
ivan.miljeno...@gmail.com> wrote:
> Jason Dagit writes:
>
> > On Fri, Apr 30, 2010 at 11:08 PM, Ivan Lazar Miljenovic <
> > ivan.miljeno...@gmail.com> wrote:
> >>
> >>
> >> You're putting the constraint in the wrong places: put the "(Cls a
Sorry for the useless noise, I realised just after I sent this that
that is what Jason said initially :s
On 1 May 2010 17:02, Ivan Lazar Miljenovic wrote:
> "Brandon S. Allbery KF8NH" writes:
>
>> On May 1, 2010, at 02:38 , Jason Dagit wrote:
>>> Why wasn't the Graph class designed this way? My
"Brandon S. Allbery KF8NH" writes:
> On May 1, 2010, at 02:38 , Jason Dagit wrote:
>> Why wasn't the Graph class designed this way? My guess: It was
>> probably a decision that predated multiparameter type classes.
>
>
> Or a specific decision was made to stick to Haskell'98 compatibility.
I w
Jason Dagit writes:
> On Fri, Apr 30, 2010 at 11:30 PM, Jason Dagit wrote:
> Looking over this real quick, I think the Graph class should be changed to
> mention a and b:
>
> class Graph (gr a b) where ...
Won't work: you need to specify that gr has kind * -> * -> *; this is
exactly the same a
Jason Dagit writes:
> On Fri, Apr 30, 2010 at 11:08 PM, Ivan Lazar Miljenovic <
> ivan.miljeno...@gmail.com> wrote:
>>
>>
>> You're putting the constraint in the wrong places: put the "(Cls a) => "
>> in the actual functions where you need it.
>>
>
> That's solid advice in general, but it's still
On May 1, 2010, at 02:38 , Jason Dagit wrote:
Why wasn't the Graph class designed this way? My guess: It was
probably a decision that predated multiparameter type classes.
Or a specific decision was made to stick to Haskell'98 compatibility.
--
brandon s. allbery [solaris,freebsd,perl,pugs
On Fri, Apr 30, 2010 at 11:30 PM, Jason Dagit wrote:
>
>
> On Fri, Apr 30, 2010 at 11:08 PM, Ivan Lazar Miljenovic <
> ivan.miljeno...@gmail.com> wrote:
>>
>>
>> You're putting the constraint in the wrong places: put the "(Cls a) => "
>> in the actual functions where you need it.
>>
>
> That's so
On Fri, Apr 30, 2010 at 11:08 PM, Ivan Lazar Miljenovic <
ivan.miljeno...@gmail.com> wrote:
>
>
> You're putting the constraint in the wrong places: put the "(Cls a) => "
> in the actual functions where you need it.
>
That's solid advice in general, but it's still not going to work here if any
of
"Kevin Quick" writes:
> I need help understanding how to express the following:
>
>
>> data (Cls a) => B a = B [a]
I think this only works if you have a forall in there.
>
>> data GrB a b = GrB (B a)
>
>> instance Graph GrB where ...
>
> In the methods for the instance specification, I need
I need help understanding how to express the following:
data (Cls a) => B a = B [a]
data GrB a b = GrB (B a)
instance Graph GrB where ...
In the methods for the instance specification, I need to perform Cls a
operations on a.
* As shown, the compiler complains that it cannot dedu
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