Proposal: Add a strict version of <$> for monads

[Gregory Collins]

Obvious +1.


On Fri, Nov 29, 2013 at 1:07 PM, Johan Tibell <johan.tibell at gmail.com>wrote:

> Hi all,
>
> I propose we add a strict version of <$> to base:
>
>     -- | A strict version of 'Data.Functor.<$>' for monads.
>     (<$!>) :: Monad m => (a -> b) -> m a -> m b
>     f <$!> m = do
>         a <- m
>         return $! f a
>     {-# INLINE (<$!>) #-}
>
>     infixl 4 <$!>
>
> It works on Monads instead of Functors as required by us inspecting the
> argument.
>
> This version is highly convenient if you want to work with
> functors/applicatives in e.g. parser and avoid spurious thunks at the same
> time. I realized that it was needed while fixing large space usage (but not
> space-leak) issues in cassava.
>
> I believe Edward Kmett discovered the need for it independently as well.
>
> Deadline: 3 weeks
>
> Cheers,
> Johan
>
>
> _______________________________________________
> Libraries mailing list
> Libraries at haskell.org
> http://www.haskell.org/mailman/listinfo/libraries
>
>


-- 
Gregory Collins <greg at gregorycollins.net>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://www.haskell.org/pipermail/libraries/attachments/20131129/49ebe8fd/attachment.html>