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