2009/3/26 Jason Dusek <jason.du...@gmail.com>: > 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.
I'm not sure if there is a bad interaction with rewrite rules (which I assume was the complaint) but single method dictionaries tend to be faster because they are represented by a coercion in the Core language, which means that packing and unpacking the dictionary is free at runtime. Cheers, Max _______________________________________________ Glasgow-haskell-users mailing list Glasgow-haskell-users@haskell.org http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
