Extensive Memory usage (regression)
The "bling raytracer" project  can not be compiled with recent GHC versions (personally tested 7.4.1 on Linux / OS X / Windows, that 7.4.2 fails in the same way was reported on IRC).
The problem is that when compiling the "Transform.hs" source file  GHC allocates more RAM than any of my machines can bear (8+ GB).
This does not happen with 7.0.x versions of GHC. Also, reducing the optimization level from O2 to O1 makes the problem go away. To reproduce this bug I'd recommend
hg clone -r eb0f7f91bde6 https://code.google.com/p/bling-raytracer/ cabal build
There was no consensus on IRC if this is really a GHC bug or I should simply tinker with the GHC options / source file until it works. But since the code in question does not use any obscure extensions (in fact, no extensions at all) and could be compiled with many GHC versions from 6.4 onward, I thought you might want to hear about it.