ghci> [$rx|([aeiou]).*(er|ing|tion)([\.,\?]*)$|] "helloing.!?!?!"
 Just ["elloing.!?!?!","e","ing",".!?!?!"]

 ghci> tail `fmap` [$rx|^([+-])?([0-9]+)\.([0-9]+)|] (show $ negate pi)
 Just ["-","3","141592653589793"]

 ghci> maybe [] tail $ [$rx|^([+-])?([0-9]+)\.([0-9]+)|] (show $ negate pi)
 ["-","3","141592653589793"]