On 03/12/2009 14:12, Henning Thielemann wrote:
On Thu, 3 Dec 2009, Malcolm Wallace wrote:
#3709: Data.Either.partitionEithers is not lazy enough
This is a behavioural change, e.g.:
Main> case partitionEithers1 [Left 'a', error "Not me"] of (x : _, _)
-> x
Program error: Not me
Main> case partitionEithers2 [Left 'a', error "Not me"] of (x : _, _)
-> x
'a'
Yes, and isn't that the point of the bugfix? No non-bottoming program
has changed, but fewer programs fail now. I find it hard to imagine
that anyone could have been relying on getting a crash here.
Making something more lazy can cause a memory leak.
and a time leak, or a stack overflow. People might complain if we made
foldl' more lazy :-)
Cheers,
Simon
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