SevenThunders wrote: > > I have run into a baffling distinction between the behavior of GHCi and > the compiled binary from GHC. > I suspect it's something pretty stupid on my part. > > I have the following test program > <test.hs> > import Matrix > > main = let > f1 = bRgauss 4 3 > f2 = bRgauss 3 2 > fu = f1 *. f2 > in bsave "fumat" fu > ---------------------------------- > The type signature of bsave is > > > -- | save a matrix to a file > bsave :: String -> m -> IO() > bsave str z = do > k <- matindx z > withCString str (\x -> bmsave x k) > > and bmsave is a C routine that does a simple write to disk using fprintf. > If I compile using GHC and run this as test.exe it does absolutely > nothing, no file is actually saved. In fact no file is saved even > if I try to print components of fu in the IO monad. > > Whereas if I load it into GHCi and run main, everything works as > expected. Well sort of. Apparently everytime I extract something out > of fu and use it in an IO monad it executes all the IO actions in fu, so > it's easy to get unwanted behavior with incautious use. > > > _______________________________________________ > Haskell-Cafe mailing list > Haskell-Cafe@haskell.org > http://www.haskell.org/mailman/listinfo/haskell-cafe > >
OK it was stupid. Apparently GHC behaves differently according to what the name of the high level source file is. If I renamed test.hc to main.hc everything works the same as GHCi. I probably should actually read the manual some day. -- View this message in context: http://www.nabble.com/Baffled-by-Disk-IO-tf2021760.html#a5559084 Sent from the Haskell - Haskell-Cafe forum at Nabble.com. _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe