This subdirectory is used for packing up the entire Reason refmt into a single file through BuckleScript's bspack, thus discarding all intermediate steps needed to build Reason, except for the final refmt binary compilation. Likewise for reactjs_jsx_ppx.
This makes our installation much friendlier to e.g. Windows. BuckleScript currently includes the two bundles in its own repo, thus making Reason first-class.
Make sure you did npm install in the root directory and in this directory. Then: ./reason_bspack.sh.