Make.Pair
The pair interface lifted into the monad.
val fst : ('a * 'b) T(M).t -> 'a T(M).t
fst (x,y) computes x
fst (x,y)
x
val snd : ('a * 'b) T(M).t -> 'b T(M).t
snd (x,y) computes y
snd (x,y)
y