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

[Richard O'Keefe]

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

> On 3 August 2010 01:34, Richard O'Keefe <ok at cs.otago.ac.nz> 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.