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README.markdown

hsb2hs

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 ()

  })

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Preprocessor for inserting literals with binary blobs into Haskell programs.

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