On 25/09/10 12:30, Ian Lynagh wrote:
On Sat, Sep 25, 2010 at 03:45:15AM +0200, Daniel Fischer wrote:
On Saturday 25 September 2010 02:55:24, Ian Lynagh wrote:
On Fri, Sep 24, 2010 at 09:21:19PM +0200, Daniel Fischer wrote:
Proposal: A stricter implementation of lines.
Reason: The current implementation causes a space leak (cf. http://homepages.inf.ed.ac.uk/wadler/papers/leak/leak.ps), at least in GHC.
The proposed implementation fixes the leak at the small cost of being stricter if the first _|_ in the String is the first character of a line.
I think this changes the definition from one that currently has a space leak with GHC, to one which necessarily must have a space leak (as all of l must be held in memory while we look for a newline).
No, with the proposed implementation, e.g. counting line lengths runs in constant space:
Ah, yes, you are right, sorry. I don't have a strong opinion, then.
We ought to put the old definition into the H98 and H2010 packages, though. Hmm, but currently Prelude always comes from base.
Actually the haskell2010 package has its own Prelude, which could be different from the one in base if we wish. Cheers, Simon