[Haskell-cafe] Smarter do notation

Thomas Schilling nominolo at googlemail.com
Mon Sep 5 23:41:02 CEST 2011

On 5 September 2011 15:49, Sebastian Fischer <fischer at nii.ac.jp> wrote:
> On Mon, Sep 5, 2011 at 10:19 PM, Thomas Schilling <nominolo at googlemail.com> wrote:
>>> a >>= \p -> f <$> b -- 'free p' and 'free b' disjoint
>>>  -->
>>> ((\p -> f) <$> a) <*> b
>> Will there also be an optimisation for some sort of simple patterns?  I.e., where we could rewrite this to:
>>   liftA2 (\pa pb -> f ...) a b
>> I think I remember someone saying that the one-at-a-time application of <*> inhibits certain optimisations.
> liftA2 is defined via one-at-a-time application and cannot be redefined because it is no method of Applicative. Do you remember more details?

Good point.  I can't find the original post, so I don't know what
exactly the issue was (or maybe I'm misremembering).

Push the envelope. Watch it bend.

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