On 2014-11-28 05:11 PM, Dan Piponi wrote:

In my code I have this line:

foreign import ccall "set_num_states" setNumStates :: Int -> IO ()

I can build my project using cabal and have an appropriate "c-sources:" line.

But when I use ghc-mod check (eg. from " ghc-mod-5.2.0.0", and launched from Syntastic) it complains:

"ghc-mod: ByteCodeLink: can't find label During interactive linking, GHCi couldn't find the following symbol: set_num_states"

How should I be checking my code?

I don't know about ghc-mod. But I know ghci, and you may be able to lift ghci things to ghc-mod things. "ghci M.hs" or "ghci" and then ":load M.hs" gives the same error. However, you're expected to: (if your C file is s.c) "ghci s.o M.hs" or "ghci M.hs s.o" or "ghci s.o" and then ":load M.hs" that's how ghci knows where to find set_num_states. See also GHC user's guide section 2.6.2.