Monads are used not only for programming IO, state, exceptions etc, but also are the foundation of lists. It is hard to imagine functional programming without this basic datatype. Sets, Bags, trees etc are also monads. Phil Wadler wrote a very useful paper Comprehending Monads which I notice is not found on the Haskell/bookshelf web page. It can be found at http://www.cs.bell-labs.com/who/wadler/topics/monads.html I recommend this page for anyone interested in monads. --PeterD

-----Original Message----- From: Mads Skagen [mailto:bedloose@yahoo.dk] Sent: Thursday, May 17, 2001 4:25 AM To: haskell@haskell.org Subject: Monads

Hi

I'v currently working on a school-project where I have to describe the Haskell programming language.

I've been looking through Monads and especially the IO monad, the Maybe monad and the list monad

My question is why are monads necessary in the language ?

Is it not possible to construct the features provided by Monads using basic functional constructs ?

What do I gain using Monads ?

Thank you very much.

Regards Skagen