[boost] [fusion] Any chance we can incorporate more folds?

Subject: [boost] [fusion] Any chance we can incorporate more folds?
From: David Sankel (camior_at_[hidden])
Date: 2010-08-20 16:43:27

I've implemented, in particular, foldr1:

template<
typename Sequence,
typename State,
typename F
>
typename result_of::foldr1<Sequence, F>::type foldr1(
Sequence& seq, F const& f);

Semantics:

Equivalent to f(....f(f(e1,e2),e3)...) where e1 ...eN are the elements
of seq.

It is very useful for fusion sequences of possibly distinct types that have
identical concepts which can be merged in some way (like generators).

I very much like the folds that are included in Haskell's prelude, namely
foldl, foldl1, foldr (somewhat like boost's fold), and foldr1[1].

David

[1]
http://www.haskell.org/onlinereport/haskell2010/haskellch20.html#x28-23100020.3

-- 
David Sankel
Sankel Software
www.sankelsoftware.com
585 617 4748 (Office)