Odds.DiceThe Odds library never handles Randomness. Instead, it is up to the user of the library to install a handler for this Roll faces effect, continuing with a random number from 1 to faces inclusive.
fold f init rolls faces folds f over rolls rolls of a faces-faced die starting with init.
E.g., fold max 0 2 20 takes the best of two d20 rolls.
val eval : formula -> int