Pattern match checking

Simon Peyton Jones simonpj at
Tue Jan 12 15:40:49 UTC 2016

I believe that your #1 priority on the GHC pattern matching front is to make it so that the pattern checker will give up if it examines more than 1,000 (or whatever, there should be a settable limit) cases in the pruner.
This should cure all the performance problems at once, at the cost of giving up on the exhaustiveness check for that function.
This is a small, local, single change; should not take long.  When do you think you’ll be done with that?
I am (very) ambitious to do a better job, and we discussed various approaches.  But the First Thing is to stop GHC consuming infinite time.
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