Proposal for deepseq: Data.Sequence.Seq instance for NFData

Alexey Karakulov ankarakulov at
Tue Jul 12 17:21:15 CEST 2011

My proposal is qiute straightforward. The patch is attached and it's essence
is in these lines:

> instance NFData a => NFData (Data.Sequence.Seq a) where
>    rnf = rnf . Foldable.toList

[Discussion part]

I choosed toList method to keep the code style, but I'm not sure it's
efficient to create cons'es when we could just fold:

> rnfFoldable :: (NFData a, Foldable f) => f a -> ()
> rnfFoldable = Foldable.foldMap rnf

Or it's better to do this with foldl (while not so nice at is was with using
() as monoid):

> rnfFoldable = Foldable.foldl (const rnf) ()

There was a proposal to add strict folds to Foldable type class, so we can
use foldl' there.

My proposal is to add the instance in either way.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: deepseq.patch
Type: text/x-patch
Size: 1029 bytes
Desc: not available
URL: <>

More information about the Libraries mailing list