Proposal: Export Data.Word.Word from Prelude

[Carter Schonwald]

wait the proposal wasn't for including Intx and Wordx in prelude? ('cause
I'd support that strongly! )


On Wed, Aug 13, 2014 at 7:25 PM, John Lato <jwlato at gmail.com> wrote:

> On Wed, Aug 13, 2014 at 4:05 PM, Evan Laforge <qdunkan at gmail.com> wrote:
>
>> On Wed, Aug 13, 2014 at 3:06 PM, Ben Millwood <haskell at benmachine.co.uk>
>> wrote:
>> > `length :: [a] -> Word` (or things of that ilk) would be even more of a
>> > mistake, because type inference will spread that `Word` everywhere, and
>> `2 -
>> > 3 :: Word` is catastrophically wrong.
>>
>> This is a pretty convincing argument for me.  I have in the past used
>> Word for things that seemed like they should always be positive, and
>> pretty quickly reverted back to a signed type.  All you need is a
>> subtraction anywhere and the chance of underflow is very high.  And,
>> as Ben said, it's easy for the "always positive" type to wind up in a
>> domain where subtraction is valid due to type inference.  The
>> principled thing might be to make that a different type, but in
>> practice that can be a lot of hassle so it often doesn't happen (do
>> you use NonEmpty everywhere possible? always have separate types for
>> absolute and relative measures? sometimes it's not worth the clutter).
>
>
> I agree it would be wrong to have `length` return a Word unconditionally,
> but I don't think it's a mistake in general to have that option available
> (i.e. genericLength).  It just means that the programmer is taking on some
> responsibilities manually instead of leveraging the type system, but
> sometimes that's the only way to get the desired performance.  Besides,
> nobody is actually proposing that `length` return a Word, so I don't find
> this argument relevant to the proposal.
>
> Relatively weak +1 from me (I'm more enthusiastic about exporting the
> entirely of Intx/Wordx types via the prelude).
>
> John L.
>
>
>
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