Proposal: NF newtype

[Edward Z. Yang]

That's what I get for guessing syntax. Fixed.

Edward

Excerpts from Michael Snoyman's message of 2015-04-22 08:54:32 +0100:
> Small request: could you bump the upper bound to allow base 4? ;)
> 
> On Wed, Apr 22, 2015 at 10:50 AM Edward Z. Yang <ezyang at mit.edu> wrote:
> 
> > Hello all,
> >
> > Taking the appropriate suggestion, I have created a small
> > package to provide this functionality:
> >
> >     https://hackage.haskell.org/package/nf
> >
> > If it migrates into deepseq, we can update this package to reexport
> > the appropriate modules from deepseq when it is available.
> >
> > Please let me know if there's anything (e.g. version bounds) which
> > I can do to make this more "enterprise" ready.
> >
> > Cheers,
> > Edward
> >
> > Excerpts from Edward Z. Yang's message of 2015-02-10 08:46:37 +0000:
> > > I propose the following (abstract) data type, functions, and instance be
> > > added to deepseq (naming amenable to bikeshedding):
> > >
> > >     newtype NF a = NF a -- abstract
> > >     makeNF :: NFData a => a -> NF a
> > >     getNF :: NF a -> a
> > >     instance NFData (NF a) where
> > >         rnf x = x `seq` ()
> > >
> > > NF is an abstract data type representing data which has been evaluated
> > > to normal form; the guarantee specifically is, if NF is in whnf, then
> > > it is in nf.  Crucially, when we have 'NF a', we ONLY need to seq it
> > > in order to assure that it is fully evaluated.
> > >
> > > This guarantee is sufficient for a variety of cases where
> > > normal data is necessary, e.g. when transmitting data over Channels.
> > > For example, from the monad-par library 'put_' could be used in place
> > > of 'put' with this type signature.
> > >
> > >     put_ :: IVar (NF a) -> (NF a) -> Par ()
> > >
> > > Cheers,
> > > Edward
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