Re: [ghc-steering-committee] #380 GHC2021: Voting starts

On Sun, Nov 29, 2020 at 12:40 PM Simon Marlow wrote:

On Wed, 25 Nov 2020 at 11:21, Spiwack, Arnaud wrote:

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PostfixOperators: maybe

I'd like to make a case for this extension, on the grounds that it's a complete no-brainer.

The name "PostfixOperators" makes it sound a lot more scary than it actually is. In fact it's just a tiny generalisation to the definition of left sections. You could almost regard it as a typo in the Haskell report - if it had been noticed that this rule was unnecessarily restrictive, I'm fairly sure it would have been fixed at the time.

https://downloads.haskell.org/ghc/latest/docs/html/users_guide/glasgow_exts....

It took me several readings to understand what this extension does, to be honest. I agree now, I'll change my vote. On Sun, Nov 29, 2020 at 9:14 PM Alejandro Serrano Mena wrote:

El dom, 29 nov 2020 a las 12:12, Simon Marlow () escribió:

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On Wed, 25 Nov 2020 at 11:21, Spiwack, Arnaud wrote:

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## OverloadedX

These extensions can confuse type inference, yielding ambiguous type variables message. And as much as I like them, I don't think it's safe to include them yet. Not until we have a reasonable story for defaulting literals.

OverloadedLabels: no OverloadedLists: no OverloadedStrings: no

For what it's worth, I've been writing code with OverloadedStrings for several years now and in my experience it rarely causes a problem, even for beginners. The context almost always provides enough information to resolve the ambiguity. (admittedly I'm slightly surprised by this too, but experience has convinced me)

I don't have much experience with OverloadedLists, but I'd be prepared to believe that it's a similar story there too.

Adding to this, I think that both OverloadedStrings and OverloadedLists go very well with the idea of overloaded literals story that Haskell already has for numbers.

On principle, I very much agree. In fact I almost always turn both OverloadedStrings and OverloadedList on. But it also almost always causes some type errors when I turn them on (well, ambiguity errors). Therefore, I'm a bit dubious at the idea of making them the default. Even though Alejandro's point is undeniable.