When I compile a simple code importing Control.Monad.State with ghc-6.4.20050217 on Linux I get linking errors: % cat foo.hs import Control.Monad.State main = putStr "Hello\n" % ghc foo.hs foo.o(.text+0x145): In function `__stginit_Main_': : undefined reference to `__stginit_ControlziMonadziState_' collect2: ld returned 1 exit status % The same works with the --make option: % ghc --make foo.hs Chasing modules from: foo.hs Compiling Main ( foo.hs, foo.o ) Linking ... % I tried both the linux binary and to compile GHC from source. Akos -- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Akos Korosmezey Tel: +36-1-439-5936 Ericsson Telecom Ltd. ETH/GSCD/RUNB Fax: +36-1-437-7576 P.O.B. 107, H-1300 Budapest, Hungary Home: +36-26-342-687 mailto:Akos.Korosmezey@ericsson.com Mobile: +36-30-740-7732 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~