Request for comment on new package

[David Feuer]

A while back I complained to Ed Kmett that the `Bifunctor` instance for (,)
isn't strictly law abiding. Specifically,

  bimap id id _|_ = (_|_, _|_)

while by the first law we should really have

  bimap id id _|_ = _|_

He countered that for some purposes the extra laziness is necessary, and
that it's rather less convenient to lazify a pair than to force one (unless
you use something like forcePair[*] from utility-ht, which is another
one-trick pony to remember). This package is my attempt to prove to Ed that
lazifying is almost as easy as strictifying.

[*]
http://hackage.haskell.org/package/utility-ht-0.0.14/docs/Data-Tuple-Lazy.html#v:forcePair

On Tue, Aug 6, 2019, 3:55 AM Chris Wong <lambda.fairy at gmail.com> wrote:

> Hi David,
>
> What are the use cases for such a package?
>
> I'd love to see some examples of problems that can be solved with
> Lazifiable.
>
> Chris
>
>
> On Tue, Aug 6, 2019, 19:25 David Feuer <david.feuer at gmail.com> wrote:
>
>> I've put together a small package for lazifying record types. There's a
>> "classy" version in Data.Lazify and a Generic-only version in
>> Data.Lazify.Generic. A few examples are below. I'd love to hear comments on
>> what looks good and what should be changed before I make the first release.
>> As usual, names are the hardest part. Note especially that the operator
>> ($~) is defined in *both* Data.Lazify and Data.Lazify.Generic, and that no
>> operator corresponds to genericLazify. Hrmm mumble.
>>
>> lazify (1, 2) = (1, 2)
>> lazify undefined = (_|_, _|_, _|_)
>> lazify undefined = Sum (_|_, _|_, _|_)
>>
>> genericLazify (1,2) = (1,2)
>> genericLazify undefined = (_|_, _|_, _|_)
>> genericLazify (Sum (MyCon x y)) = ... oops, MyType isn't an instance of
>> Lazifiable
>>
>> lazifyGeneric (1,2) = (1,2)
>> lazifyGeneric undefined = (_|_, _|_, _|_)
>> lazifyGeneric (Sum (MyCon x y)) = Sum (MyCon x y)
>>
>> Thanks in advance,
>> David
>> _______________________________________________
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>>
>
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