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The docs <http://www.haskell.org/ghc/docs/latest/html/users_guide/ffi-ghc.html#glasgow-foreign-headers> say that -#include pragmas no longer work, but fail to explain how to load code without them. Suffice to say I have no recourse but trial and error."

Ah, now that is a GHC documentation question. Can you tell us what should the docs should say instead? Then we can fix the docs.

- I believe I would say (agreeing with M Parès) that hsc2hs serves this purpose - put "#include <termios.h>" in the .hsc file and use hsc2hs features like #const and (#peek x, y). The termios example could cover a lot more ground by operating on the termios struct and calling tcsetattr directly from Haskell, using hsc2hs # macros (I append an example implementation), but you'd also want to explain that hsc2hs is only needed for these # macros, not for FFI in general. But hsc2hs as of GHC 7.0.3 generates a "{-# INCLUDE" pragma, which of course is cause for complaint from ghc. So there might be more to be fixed, beyond just the documentation. That line probably has no actual purpose other than to annoy ghc, and as a workaround it can simply be removed from the .hs file. - My impression is that Greencard isn't the best way to get started with FFI and hasn't been for a decade or so, so it should probably be purged from docs. - The "root" page needs some attention from someone who understands what "safe" and "unsafe" mean. Currently (under "Improving efficiency") it cites the conventional interpretation that a function must be "safe" if it calls back into the runtime, but neglects to mention that it must also be "safe" if it is not to block execution of other threads, including bound OS threads - so related to efficiency issues you might want to make any slow I/O operation "safe" to avoid this. There may be other points about "unsafe" that need to be documented. Donn -------- {-# LANGUAGE ForeignFunctionInterface #-} module TTY (clearICANON) where import Data.Word (Word32) import Foreign import Foreign.C #include <termios.h> type TCFlag = (#type tcflag_t) type Speed = (#type speed_t) data Termios = Termios { termios_c_iflag :: TCFlag , termios_c_oflag :: TCFlag , termios_c_cflag :: TCFlag , termios_c_lflag :: TCFlag , termios_c_cc :: [CChar] , termios_c_ispeed :: Speed , termios_c_ospeed :: Speed } deriving Show instance Storable Termios where sizeOf _ = #size struct termios alignment _ = alignment (undefined::CDouble) peek a = do iflag <- (#peek struct termios, c_iflag) a oflag <- (#peek struct termios, c_oflag) a cflag <- (#peek struct termios, c_cflag) a lflag <- (#peek struct termios, c_lflag) a cc <- peekArray 20 ((#ptr struct termios, c_cc) a) ispeed <- (#peek struct termios, c_ispeed) a ospeed <- (#peek struct termios, c_ospeed) a return (Termios iflag oflag cflag lflag cc ispeed ospeed) poke a (Termios iflag oflag cflag lflag cc ispeed ospeed) = do (#poke struct termios, c_iflag) a iflag (#poke struct termios, c_oflag) a oflag (#poke struct termios, c_cflag) a cflag (#poke struct termios, c_lflag) a lflag pokeArray ((#ptr struct termios, c_cc) a) (take 20 (cc ++ repeat 0)) (#poke struct termios, c_ispeed) a ispeed (#poke struct termios, c_ospeed) a ospeed foreign import ccall "tcgetattr" tcgetattr :: CInt -> Ptr Termios -> IO CInt foreign import ccall "tcsetattr" tcsetattr :: CInt -> CInt -> Ptr Termios -> IO CInt setLFlag :: TCFlag -> Termios -> Termios setLFlag c a = a { termios_c_lflag = ((termios_c_lflag a) .|. c) } clearLFlag :: TCFlag -> Termios -> Termios clearLFlag c a = a { termios_c_lflag = ((termios_c_lflag a) .&. (complement c)) } setTTYAttr :: CInt -> (Termios -> Termios) -> IO () setTTYAttr fd fn = alloca $ \ termiosp -> do status <- tcgetattr fd termiosp if status == 0 then do termios <- peek termiosp poke termiosp (fn termios) status <- tcsetattr fd (#const TCSAFLUSH) termiosp if status == 0 then return () else throwErrno "tcgetattr" else throwErrno "tcgetattr" clearICANON = setTTYAttr 0 (clearLFlag (#const ICANON))