28 Oct
2008
28 Oct
'08
4:26 a.m.
2008/10/27 Dougal Stanton
This happens when, for example, your code imports a library which was compiled with a previous version of bytestring. Replacing bytestring on its own isn't enough to solve the problem. To make things more awkward, it could be several libraries which use the old bytestring. Using "ghc --make", it seems this error can be ignored, but it's annoying if you want to use the interactive GHC.
The problem is GHCi's linker. It cannot deal with duplicate symbols, while 'ld' can. I know of no workaround to get it to work, though. You could try to hide the new bytestring, so that ghci doesn't find it. FWIW, 6.10.1 will come with a recent version of bytestring, so separately upgrading should no longer be necessary.