JSONb

JSON parser that uses byte strings.

This parser consumes lazy ByteStrings to produce JSON in a simple, efficient format backed with strict ByteStrings, Rationals and ByteString tries. See the schema generation tools and the command line JSON schema generator (in the examples subdir) for an example of how to use the parsing tools.

Have you considered aeson (http://hackage.haskell.org/package/aeson), a newer, extensively benchmarked JSON parsing library?