Re: [Haskell-cafe] Re: Can we come out of a monad?

On Aug 3, 2010, at 11:37 PM, Christopher Witte wrote:

On 3 August 2010 01:34, Richard O'Keefe wrote: There's a thing I'm still finding extremely hard about monads, and that's how to get into the frame of mind where inventing things like Monad and Applicative and Arrows is something I could do myself. Functor, yes, I could have invented Functor. But not the others.

Maybe looking at Sigfpe's blog post You Could Have Invented Monads! (And Maybe You Already Have.) will help.

Notice the tense, "could have". I have read You Could Have Invented Monads, and recommended it to students. In fact I _did_ invent monads, in the guise of parser combinators. That is to say, having heard of parser combinators, I developed my own set, which contained operations recognisable with hindsight as the operations of Monad and MonadPlus &c BUT I DID NOT REALISE THAT THAT WAS WHAT I HAD DONE. After reading that blog post, yes.