On 26 July 2013 03:19, Jonathan S. Shapiro <[email protected]> wrote:
> On Wed, Jul 24, 2013 at 2:57 PM, David Jeske <[email protected]> wrote:
>> If it was valuable to agree on the Ord implementation, presumably we would
>> be using a version of sort which parameterized the ord-comparator itself.
>
>
> You are arguing, in effect, that the choice of inlining strategy determines
> whether something is valuable. If so, that's complete nonsense.
>
> Parameterizing the ord-comparator makes sense only if we want to be able to
> sort in different ways at different times. Knowing what the standard
> ordering is is a matter of understanding the reference behavior of the
> procedure being called.
I keep going back over this conversation - I think you both raised an
interesting point, and I keep thinking that Shap is talking about the
int typeclass used for comparing array indexes when he's not. Maybe I
missed it, but I guess you're not trying to argue that typeclasses
that were not inferred from parametric argument types need to be
represented in the signature; not sure why I thought that.
Given these two signatures (with apologies for mixing the syntaxes of
four different languages to make it sufficiently expressive)
sort : {{x : Ord X}} -> x[n] %r -(mut %r)-> ()
sortR : R[n] %r -(mut %r)-> ()
where
sortR = sort {{ordR}}
in one crate, I later come along and say, well, I'd really like to
sort my array of R by the ordR ordering and so write
sort {{ordR}} rs
and that really, I probably hope to get sortR. So, besides actually
using sortR, is there a way I can get the correct sort instance AND
have it inlined and fast, since I've already compiled that?
I think that what you're trying to say, Shap, is that you would like a
way to compile the partial application and then retrieve it when I
make the same application. Which is really nothing about classes that
don't appear in signatures, because if you want to use a particular
ordering, you probably wouldn't use sortR because it doesn't take an
Ord instance.
Am I on the right track?
--
William Leslie
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