I fear there is certain misunderstanding about -O usage with ghc-5.00 interactive. Simon Marlow and User's Guide (Section 4.4) say that

-O does not work with ghci. For technical reason, the bytecode compiler doesn't interact well with one of the optimization passes [..]

What is a bytecode compiler? The one that prepares a lightly compiled code for the interpreter? What I meant is something like this: to compile ghc -c -O Foo.hs in the batch mode and then run ghci ... Preude> :load Foo ... Foo> sm [1..9999000] I tried this with certain small function Foo.sm, and it works, and runs better than when compied with -Onot. Now, as I see that ghci can load and run the code made by -O, I wonder what the User's Guide means by saying "-O does not work with GHCi". Maybe ghci -O ? could be meaningful? ----------------- Serge Mechveliani mechvel@botik.ru