hsb2hs is a preprocessor that allows you to include binary blobs as literals in your Haskell programs and libraries. Running hsb2hs on a file containing
foo :: ByteString
foo = %blob "data/foo.txt"
will produce a file containing
foo :: ByteString
foo = "here's my data"
where data/foo.txt is a text file containing the string
"here's my data." (Note that the literal "here's my data"
can be interpreted either as a String or, with OverloadedStrings,
as a ByteString.)
If you have a whole directory of data files, you can get an association list instead:
bar :: [(FilePath, ByteString)]
bar = %blob "images"
hsb2hs is set up to use as a preprocessor in the Haskell build
procedure. Put your blob instructions in .hsb files, and Cabal will
automatically convert these to .hs files during the build.
To use hsb2hs with Cabal, set Build-type to Custom' and use something like the following for your
Setup.hs`:
import Distribution.Simple
import Distribution.Simple.PreProcess
import Distribution.Simple.Utils (info)
import System.Directory
import System.Process
import System.Exit
main :: IO ()
main = defaultMainWithHooks simpleUserHooks{
hookedPreProcessors = [ppBlobSuffixHandler]
}
ppBlobSuffixHandler :: PPSuffixHandler
ppBlobSuffixHandler = ("hsb", \_ _ ->
PreProcessor {
platformIndependent = True,
runPreProcessor = mkSimplePreProcessor $ \infile outfile verbosity ->
do info verbosity $ "Preprocessing " ++ infile ++ " to " ++ outfile
hsb2hsPath <- findExecutable "hsb2hs"
case hsb2hsPath of
Just p -> rawSystem p [infile, infile, outfile]
Nothing -> error "hsb2hs is needed to build this program."
return ()
})