Stream: haskell-flake

Topic: Using non-haskell dependencies

Perigord (Nov 28 2024 at 08:29):

sandbox.cabal

pkgconfig-depends: libavcodec

Main.hs

foreign import capi "libavcodec/avcodec.h avcodec_version"
  c_avcodecVersion :: CInt

Just wanted to know how I would be able to add C libraries especially using the pkgconfig-depends in cabal. Currently lost on where to add pkgs.ffmpeg.lib and pkgs.ffmpeg.dev.

Notification Bot (Jan 06 2025 at 14:21):

Srid has marked this topic as unresolved.

Srid (Jan 06 2025 at 14:22):

Hmm, I think we should create a documentation page for this.

Quick answer: you need staticWhich along with extraBuildDepends. You already use the later, just need the former.

Daniel Herrera Rendón (Jan 06 2025 at 20:25):

Thanks, @Srid ! I'm a huge fan, btw.

This worked:

cowsayBin :: FilePath
cowsayBin = $(staticWhich "cowsay")

cowsay :: IO String
cowsay = do
  (_, mhout, _, _) <- createProcess (shell $ show cowsayBin <> " hola") { std_out = CreatePipe }
  case mhout of
    Just hout -> hGetContents hout
    Nothing -> pure "mhout failed"

Would staticWhichNix be a better fit?

Is there a reason this way is better?

On my previous iteration of this flake (not using haskell-flake) I used pkgs.haskell.lib.addBuildDepends this way and that worked. Are there advantages to using the which package?

Thanks again and cheers all the way from Querétaro, México : )

Srid (Jan 06 2025 at 20:29):

Great. Yes, using staticWhich basically hardcodes the full path to the binary at compile time, so it is guaranteed to be available on user's systems. Otherwise, you rely on it being in $PATH.

staticWhichNix is the same, but expects it to to be in Nix store, thus limiting your software to work only on Nix

Srid (Jan 06 2025 at 20:30):

Its implementation is simple enough to see what's going on: https://hackage.haskell.org/package/which-0.2.0.2/docs/src/System.Which.html#staticWhichNix

Daniel Herrera Rendón (Jan 06 2025 at 20:37):

I retract what I said about it working with pkgs.haskell.lib.addBuildDepends. I thought it did because I had no errors, but that was because I wasn't using it at all. I also had to use the which package to make it work on my previous flake iteration.

Last updated: Feb 05 2025 at 17:45 UTC