On Fri, Aug 10, 2007 at 06:12:03PM +0100, Andrew Coppin wrote:
[big blob of simplifier output]
Mmm. See, now, I have *no idea* what GHC is saying. But I would have expected that if I do something like
x = if testBit 3 q ...
then the definition of testBit would get inlined, and then hopfully the optimiser would do something. But then, IANAGD. (I am not a GHC developer.)
Sure, it gets inlined, and you wind up with something like: x = case 3 .&. (1 `shiftL` q) of 0 -> ... _ -> ... or, if you used the (correct and unintuitive) argument order to testBit: x = case q .&. (1 `shiftL` 3) of 0 -> ... _ -> ... We *want* (1 `shiftL` 3) to be reduced to 8 at compile time, but that doesn't seem to be happening. (And I'm not a GHC developer either. I should probably start at some point...) Stefan