Proposal: NF newtype

[Michael Snoyman]

Only thing I can think of is adding a bunch of `deriving`s to NF. I can
picture people wanting to just plot an `NF` into the middle of their data
structures and still be able to `show` it for debugging. I'm guessing a
minimal list may be Show, Read, Eq, Ord, Typeable. Data and Generic seem
like an interesting case, since- on the one hand- it would be nice to have
the instances (especially the latter) for auto-deriving mechanisms, but in
theory it can be used to break the abstraction. However, given that you're
already giving people an escape route via the .Internal module, I don't
think that's as big a concern.

On Wed, Apr 22, 2015 at 11:04 AM Edward Z. Yang <ezyang at mit.edu> wrote:

> 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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> > >
>
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