Re: Containers and strictness

On Wed, Jun 30, 2010 at 8:02 PM, Johan Tibell wrote:

On Thu, Jul 1, 2010 at 12:03 AM, Milan Straka wrote:

...

After suggestions by others I am thinking about  data Some elem = Single {-# UNPACK #-} !elem | More (Set elem) or  data Some elem = Single {-# UNPACK #-} !elem | More {-# UNPACK #-} !elem (Some elem)

Unfortunately unpacking doesn't work for polymorphic fields (the new warning for ineffective unpack pragmas in GHC head should warn about this). Given this you might as well use a standard list.

However strictness information does work. But I don't know the answer for the following questions: - Should the elements be strict even while they are not unpacked? Performance gains? - Should the spine of the list be strict? Performance gains? Space leak gains? My guess, without any benchmarks, is that both elements and the spine should be strict. In any case, for the HashMap the following data type saves the indirection of the tuples: data SomePairs key val = Pair !key !val | MorePairs !key !val !(SomePairs key val) Cheers, -- Felipe.