Proposal: Export Data.Word.Word from Prelude

[Edward Kmett]

Those would remain in Data.Int and Data.Word.

-Edward


On Wed, Aug 13, 2014 at 8:04 PM, Carter Schonwald <
carter.schonwald at gmail.com> wrote:

> 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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