On 09/29/13 08:20, Edward Kmett wrote:
I don't know that it belongs in the "standard" libraries, but there
could definitely be a package for something similar.
ConstraintKinds are a pretty hefty extension to throw at it, and the
signature written there prevents it from being used on ByteString,
Text, etc.
This can be implemented with much lighter weight types though!
class Partitionable t where
partition :: Int -> t -> [t]
I'm not sure why I don't already have this method in the
FactorialMonoid class, but I'll happily add it if anybody wants it.
Probably under the name splitEvery, since I already have splitAt.
I'm not sure this is actually the best answer to Ryan's original
plea, because I thought the idea was to let the original monoid "split
itself" in an optimal way, which would preferably be an O(1) operation.
Then again, this could be overly optimistic. For example, Map is defined as
data Map k a = Bin {-# UNPACK #-} !Size !k a !(Map k a) !(Map k a)
| Tip
so the simple O(1) split would produce three submaps, the middle one
having only one element. This operation would not be very
parallelization-friendly.
That is not particularly surprising, since parallelization was not
the main concern when Data.Map (or containers) was originally written.
The main goal, as it should have been, was optimizing the containers for
sequential execution speed. A containers-like package optimized for easy
and efficient parallelization would have to be written almost from scratch.
_______________________________________________
Haskell-Cafe mailing list
Haskell-Cafe@haskell.org
http://www.haskell.org/mailman/listinfo/haskell-cafe
