[ghc-steering-committee] #409: Exportable named defaults, Recommendation: Partial Accept

[Joachim Breitner]

Hi,

Am Dienstag, dem 29.06.2021 um 23:19 -0400 schrieb Eric Seidel:
> On Tue, Jun 29, 2021, at 22:38, Richard Eisenberg wrote:
> > Just to chime in now that I'm back in action: I'm reasonably happy with 
> > the final result here
> 
> With Richard in support, that leaves Simon PJ opposed to explicit
> imports [1]. So we have Richard opposed to implicit imports, Simon
> opposed to explicit imports, and the rest of us (I believe) amenable
> to either.

a different way to phrase that question might be: Do we want these
defaulting declarations to behave just exactly like named things, or
exactly like typeclass instances, or do we afford a new class with it’s
own exporting/importing behavior. Is that a fair assessment?

So, it doesn't really work like named things, as you don’t refer to
them in code.

But also the same design constraints as for type class instances
applies, because there is no coherence requirement (which, unless I am
mistaken, is the reason why we need no way to _not_ import an
instance).

That implies to me that this feature should be designed without too
much allusion to existing export/import behavior, and rather basing it
on what makes the feature most useful.

(sorry, this mail doesn’t get more concrete that this.)

Cheers,
Joachim



-- 
Joachim Breitner
  mail at joachim-breitner.de
  http://www.joachim-breitner.de/