Once you've got stack (the haskell tool) installed, you can set up this folder by running "stack build". Once it's set up, you can run "stack ghci" to bring up a GHCI REPL with all the relevant libraries loaded.
Once within GHCI, load the reader by running :l smsn.hs and then test it out on a file from data-public by running
fileWithText = "/SOMEWHERE-UP-TO-YOU/public/kh667uKCjKn8WzfB.smsn"
fileWithNoText = "/SOMEWHERE-UP-TO-YOU/public/zzYSwIonHKgH4EYm.smsn"
test fileWithNoText
test fileWithText