Muphrid

15 ms·

1. 1.▲
   by Muphrid 11y ago

   That operation is called fmap, and it's characteristic of a functor. In Haskell, it's called liftM for monads, but they're really the same thing (and I think recent proposals are going to iron out this redundancy). fmap is on
2. 2.▲
   by Muphrid 11y ago

   No, plain functors, applicative functors, and monads each deal with a different potential use case. Look at the specific type signatures: plain functor - fmap: (a -> b) -> (F a -> F b) applicative functor - ap: A (a -> b)
3. 3.▲
   by Muphrid 11y ago

   The order of operations here is "right associative". So A -> B -> C -> D is equivalent to any of the following A -> (B -> C -> D) A -> (B -> (C -> D)) A -> B -> (C -> D) They&#
4. 4.▲
   by Muphrid 11y ago

   Whoever told you it has to do with IO and functional purity vastly oversimplified things. That is just one use case. Monads take care of a very common computation pattern: wrapping and unwrapping data from a container to do stuff with it.