Hi, In the ghc manual I read : "How do I find out a function's strictness?" Don't guess-look it up. Look for your function in the interface file, then for the third field in the pragma; it should say __S <string>. The <string> gives the strictness of the function's arguments. L is lazy (bad), S and E are strict (good), P is "primitive" (good), U(...) is strict and "unpackable" (very good), and A is absent (very good). -- When I look in the *.hi binary files generated by ghc with ghc --show-iface, I don't see anything like "__S" anywhere. Where should I look ? Thank you Francis Girard francis.girard@free.fr LE CONQUET, France