Proposal: Add an analogue of $! to deepseq

[Ivan Lazar Miljenovic]

The ticket for this is http://hackage.haskell.org/trac/ghc/ticket/5323

On 15 July 2011 08:49, Ivan Lazar Miljenovic <ivan.miljenovic at gmail.com> wrote:
> It's been two weeks since I raised this, and as such discussion time
> is over.  For the complete discussion, please see
> http://www.haskell.org/pipermail/libraries/2011-July/016540.html
>
> In total, there were five respondees.
>
> On 1 July 2011 17:55, Ivan Lazar Miljenovic <ivan.miljenovic at gmail.com> wrote:
>> I propose we add a operator - tentatively labelled $!! (and which
>> Hayoo reports isn't currently exported by a Hackage package) - as a
>> deepseq analogue $! to the deepseq library:
>>
>> ($!!) :: (NFData a) => (a -> b) ->a -> b
>> f $!! x = x `deepseq` f x
>>
>> infixr 0 $!!
>
> All respondees agreed with this proposal; as such it passes.
>
>> As a sub-proposal, I also propose that we add a "force" function (the
>> name of which also seems to be unused) to make it easier to test
>> forcing of values:
>>
>> force :: (NFData a) => a -> a
>> force x = x `deepseq` x
>
> * Two people agreed with this proposal.
>
> * Two people indicated that it may produce confusing results (one of
> which at least can be seen as a vote against this proposal),
>
> * The fifth respondee didn't mention it.
>
> As such, including myself in the tally, I would consider that this
> proposal passes, but that we should add sufficient documentation to
> cover Malcolm's and Sebastian's concerns (specifically that using
> force inside a left-fold would actually be more analogous to foldl
> than foldl', and that a reminder should be made that this will
> evaluate the value to NF rather than HNF, which is indeed the point).
>
> I will now go and create a ticket on the GHC Trac.
>
> @Simon: as the maintainer of deepseq, would you prefer I create a
> patch with these changes, or will you do so yourself?
>
> --
> Ivan Lazar Miljenovic
> Ivan.Miljenovic at gmail.com
> IvanMiljenovic.wordpress.com
>



-- 
Ivan Lazar Miljenovic
Ivan.Miljenovic at gmail.com
IvanMiljenovic.wordpress.com