Re: Containers and strictness

On Thu, Jul 1, 2010 at 3:38 AM, Felipe Lessa wrote:

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

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

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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?

In my experience/benchmarks strict spines are faster, probably due to better cache usage as the whole structure is updated at once. All the container data structures use strict spines. Johan