Steep learning curve and math terminology. It’s not called mappable or container, it’s called functor. It’s not called multimappable, it’s called applicable. It’s not called sequenceable, it’s called monad. It’s not called sequence stack or effect stack, it’s called monad transformer stack. This scares folks no end. (Elm did not make this mistake.)

God damn I wish we could send you back in time to when whatever idiot came up with monad etc. so you could slap some sense into them!