toDatum :: (JSON c, JSON q, JSON a, JSON e, JSON s) => ExerciseDatum -> Result (Datum c q a e s)
toDatum ExerciseStarted = return Started
toDatum :: (JSON c, JSON q, JSON a, JSON e, JSON s) => ExerciseDatum -> Result (Datum c q a e s)
toDatum ExerciseStarted = return Started
toDatum ExerciseStarted = return Started