Re: Improving void

On 6 August 2013 16:32, Malcolm Wallace wrote:

Can you explain why you think it is an improvement? To me, it looks like line noise.

I think it's becaue (<$) is a method of the Functor class, with a default definition of "fmap . const"; however, it's possible that some instances might have a custom definition which would be more efficient than using "fmap (const ())".

Regards, Malcolm

On 5/08/2013, at 20:06, Edward Kmett wrote:

Right now the definition of Control.Monad.void is:

void :: Functor f => f a -> f ()

void = fmap (const ())

I propose we replace it with

void :: Functor f => f a -> f ()

void = (() <$)

This expands out to the former definition by the default definition of (<$) and Data.Functor.Functor exports (<$) explicitly to make it possible to optimize this sort of thing. It seems a shame not to use it.

Discussion Period: 2 weeks

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