The Paragraph 4.10.7 of the GHC users guide contains this: -static Tell the linker to avoid shared Haskell libraries, if possible. This is the default. -dynamic Tell the linker to use shared Haskell libraries, if available (this option is only supported on Mac OS X at the moment, and also note that your distribution of GHC may not have been supplied with shared libraries). As I understand, this is related to the GHC own libraries. What about user-supplied libraries (listed in the `extra-libraries' field of a Cabal package description) e. g.: extra-libraries: gd, jpeg, m from http://www.cs.chalmers.se/~bringert/darcs/haskell-gd/gd.cabal There are usually files like libm.a and libm.so together in the same directory where GHC looks for libraries. Does the -static / -dynamic ghc flag affect the choice which library to link against?Or, to control this, one has to descend to the linker options, and the default would be the linker default? I believe, this is Unix-specific: AFAIR on Windows (and OS/2) dynamic implibs were indistinguishable by their names from static libraries and had the .lib suffix anyway? -- Dimitry Golubovsky Anywhere on the Web