Hi Jason,
While experimenting with Uniplate I found that 1-member dictionaries
were faster than N element dictionaries - which seems to run against
what you see in the comment. 1-member dictionaries being cheaper does
make sense as then instead of passing a tuple containing functions,
you can pass the direct function, and save yourself a (cheap) selector
call at every use.
Thanks
Neil
On Thu, Mar 26, 2009 at 11:29 PM, Jason Dusek
I was reading the stream fusion code today and came across a comment stating that single element dictionaries interacted poorly with GHC's optimizer:
class Unlifted a where
[...] expose [...]
-- | This makes GHC's optimiser happier; it sometimes produces really bad -- code for single-method dictionaries -- unlifted_dummy [...]
A cursory search on GHC's Trac shows no corresponding bug; is this no longer a problem? A small problem? I would like to know more about it.
-- Jason Dusek
|...stream fusion code...| http://www.cse.unsw.edu.au/~dons/code/streams/list/Data/Stream.hs _______________________________________________ Glasgow-haskell-users mailing list Glasgow-haskell-users@haskell.org http://www.haskell.org/mailman/listinfo/glasgow-haskell-users