[Haskell-cafe] Optimization problem

[Henning Thielemann]

On Wed, 13 Sep 2006, Magnus Jonsson wrote:

> When programming the other day I ran into this problem. What I want to do is a
> function that would work like this:
> 
> splitStreams::Ord a=>[(a,b)]->[(a,[b])]
> 
> > splitStreams [(3,x),(1,y),(3,z),(2,w)]
> [(3,[x,z]),(1,[y]),(2,[w])]

Interestingly we use such a routine in Haskore for splitting a sequence of
notes into sequences of notes of equal instruments. It's implemented
rather the same way like your version.

It's 'slice' in
   http://darcs.haskell.org/haskore/src/Haskore/Basic/TimeOrderedList.lhs
  but it is a bit more complicated because it has to manage time
information.