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Is Maybe/Option an effectful computation? Is List? I don't think it's really accurate to say this is what monads are "for". It's one use for monads but monads a

• chombier 4y ago
  > Is Maybe/Option an effectful computation Yes, Maybe/Options are a way of encoding partial functions/exceptions. List is a way of encoding non-determinism.
• codebje 4y ago
  "Effect" is perhaps a broader notion than one might think: it's an effect to write to a file or mutate some variable, sure, but it's also an effect to raise an exception, goto a label, raise an exception, execute asynchronously, be one of a set of possible outcomes, and plenty of other notions. There's a name for the monad in which there is no effect: the identity monad. The heart of a monad is the bind/flatMap/and_then interface, in which the value contained in the monad is computed on to produce a new monadic value. This is where the effect occurs: something other than just running the function happens. If the bind implementation only runs the provided function then there's no effect, and it's the identity monad.