haskell don't build 'aeson-pretty' executable. A JSON pretty-printing library compatible with aeson as well as a command-line tool to improve readabilty of streams of JSON data. The /library/ provides the function "encodePretty". It is a drop-in replacement for aeson's "encode" function, producing JSON-ByteStrings for human readers. The /command-line tool/ reads JSON from stdin and writes prettified JSON to stdout. It also offers a complementary "compact"-mode, essentially the opposite of pretty-printing. If you specify @-flib-only@ like this > cabal install -flib-only aeson-pretty the command-line tool will NOT be installed. informatikr/aeson-pretty