Dear GHC developers, The point (1) below looks like a bug (in all GHC versions!). (1) -O for demo-test. Take (the public) docon-2.10 build it under -O, install, and build also under -O its test program by cd demotest ghc $doconCpOpt -O --make Main Either the latter compilation will loop forever or it will take an unnaturally large resource. Yes, the functions T_.test, T_tt are defined in rather a particular way (see them). I always build this test under -Onot, because compiling with optimization has not much sense for this part. But slill. (2) -O2 In my DoCon programs, -O2 was always worse than -O: the code is about 1.3 times larger and 1.2 times slower. There are some particular points in my programs. For example, almost everywhere I set Integer rather than Int, I do not recall others, now. In never complained on (1) and (2) because did not recall of them and because they do not bite me in practice, so far. ----------------- Serge Mechveliani mechvel@botik.ru