Re: [Haskell-cafe] performance question

18 Jan 2005


      On Mon, Jan 17, 2005 at 08:54:38PM -0800, Ben Rudiak-Gould wrote:
...
If performance is the main concern, I would flatten the data structure:
data Interval = IlII Double Double
                 | IlIE Double Double
                 | IlEI Double Double
                 | IlEE Double Double
                 | NilII Double Double
                 | NilIE Double Double
                 | NilEI Double Double
                 | NilEE Double Double
I would go even further
...
data IntervalType = IlII 
                 | IlIE 
                 | IlEI 
                 | IlEE 
                 | NilII
                 | NilIE
                 | NilEI
                 | NilEE
   data Interval = Interval IntervalType {-# UNPACK #-} !Double {-# UNPACK #-} !Double
now, the doubles can be stored in their native form and are not under a
union data type (which always must be represented by a pointer) so
accessing them can be very fast.

        John


-- 
John Meacham - ⑆repetae.net⑆john⑈