396 B
396 B
Example: List (law verification)
Example: List is a functor (join is ⊙)
- \(M ⊙ (M ⊙ M) = (M ⊙ M) ⊙ M\)
- \(η ⊙ M = M = M ⊙ η\)
join [ join [[x,y,...,z]] ] = join [[x,y,...,z]]
= join (join [[[x,y,...,z]]])
join (η [x]) = [x] = join [η x]Therefore ([],join,η) is a monad.