On 7/16/07, Claus Reinke
enjoy (i hope:-),
Very much. Work hasn't been so much fun since.... Well, for a long time. :-) One small question, which might reveal if I've understood things aright.
(do (v,e) <- dmin' l (do guard e me <- empty m re <- nullT r write m p (v,me && re)) `mplus` return ((v,e))) `mplus` (do v <- readTVar' m re <- nullT r write m p (v,re)) `mplus` (do (v,e) <- dmin' r when e $ writeTVar' p Empty return ((v,e))) `mplus` error "emit nasal daemons"
If I refactor this a little into dminLeft dminMiddle and dminRight, I believe I should be able to replace this with: ... msum [dminLeft l m r, dminMiddle m r, dminRight r, error "emit nasal daemons"] where dminLeft l m r = do (v,e) <- dmin' l (do guard e me <- empty m re <- nullT r write m p (v,me && re)) `mplus` return (v,e) dminMiddle m r = do v <- readTVar' m re <- nullT r write m p (v,re) dminRight r = do (v,e) <- dmin' r when e $ writeTVar' p Empty return (v,e) .... Is this correct? And if so, is GHC likely to do constant folding on msum over the list skeleton? T. -- Dr Thomas Conway drtomc@gmail.com Silence is the perfectest herald of joy: I were but little happy, if I could say how much.