A few quibbles: * Purity is not at all bizarre to the real world. If I have two apples in one pile and three in the other, then merely regarding them as the sa

A few quibbles: * Purity is not at all bizarre to the real world. If I have two apples in one pile and three in the other, then merely regarding them as the same pile is (2 + 3) very, very purely. Computers are the bizarre ones! * "The first two can fail, rely on side effects and the last one is purely a side effect." It'd be much nicer to say that the first two are "side effecting computations with interesting return values" and the third one it the same... except we are not interested in the return. * "The only pure function is add". I highly doubt that `add` is pure in your example! (1) this wouldn't typecheck in Haskell now if it were and (2) it'd imply that we are just throwing away the result of the addition. * "the reason you don't see Monads in other languages is because they're not essential to them" I would challenge you to turn this exactly on it's head. The reason you don't see monads in other languages it that they are so essential to them that you cannot perceive parts without the monad.