Misleading strictness annotations in Data.List.NonEmpty

[David Feuer]

Yeah, the more I think about it, the more I like your stricter (<|). I
don't see any really useful laziness to add to groupBy1. What were you
thinking of?

On Fri, Jan 8, 2021 at 2:27 PM Keith <keith.wygant at gmail.com> wrote:
>
> There are a couple other ones that I'm less sure about.
>
> cons:
> a <| ~(b :| bs) = a :| b : bs
>
> Unsugared this is
> a <| bs = a :|
> (case bs of b :| _ -> b ) :
> case bs of _ :| bs -> bs
>
> Would this make more sense?
> a <| bs = a :| case bs of b :| bs' -> b : bs'
>
> Then
> cons x undefined = x :| undefined
> not
> x :| undefined : undefined
>
>
> groupBy1 matches strictly, could be lazy. (Is this a performance issue or an oversight?)
> —
> Sent from my phone with K-9 Mail.
>
> On January 8, 2021 6:36:58 PM UTC, Keith <keith.wygant at gmail.com> wrote:
>>
>> Thanks, will do.
>>
>> On January 8, 2021 5:07:25 PM UTC, David Feuer <david.feuer at gmail.com> wrote:
>>>
>>> The first one. Neither twiddles nor bangs are useful or add clarity.
>>>
>>> On Fri, Jan 8, 2021, 11:53 AM Keith <keith.wygant at gmail.com> wrote:
>>>
>>>>  Currently:
>>>>
>>>>  head ~(a :| _) = a
>>>>  tail ~(_ :| as) = as
>>>>
>>>>  But head and tail are both strict. At best the '~'s have no effect.
>>>>
>>>>  Should I open a PR to change it to
>>>>
>>>>  head (a :| _) = a
>>>>  tail (_ :| as) = as
>>>>
>>>>  or maybe even more clearly
>>>>
>>>>  head !(a :l _) = a
>>>>  tail !(_ :| as) = as
>>>>
>>>>  ?
>>>>  --Keith
>>>>  Sent from my phone with K-9 Mail.
>>
>>
>>
>> Good to know! Wasn't aware that that was in the works.
>>
>> And sorry for accidentally threading this onto something unrelated.
>>
>> -- Keith
>> Sent from my phone with K-9 Mail.
>>
>> On January 8, 2021 5:13:31 PM UTC, Henning Thielemann <lemming at henning-thielemann.de> wrote:
>>>
>>>
>>> On Fri, 8 Jan 2021, Keith wrote:
>>>
>>>> Currently:
>>>>
>>>> head ~(a :| _) = a
>>>> tail ~(_ :| as) = as
>>>>
>>>> But head and tail are both strict. At best the '~'s have no effect.
>>>>
>>>> Should I open a PR to change it to
>>>>
>>>> head (a :| _) = a
>>>> tail (_ :| as) = as
>>>>
>>>> or maybe even more clearly
>>>>
>>>> head !(a :l _) = a
>>>> tail !(_ :| as) = as
>>>>
>>>> ?
>>>
>>>
>>> The last one would trigger the "redundant bang pattern" warning that is
>>> going to be implemented/released:
>>>     https://gitlab.haskell.org/ghc/ghc/issues/17340
>
> _______________________________________________
> Libraries mailing list
> Libraries at haskell.org
> http://mail.haskell.org/cgi-bin/mailman/listinfo/libraries