Ryan is the monad king. Ok.. well maybe not the king. But he has a big megaphone and drops a ‘monad’ bomb daily. He has been doing some fantastic work in F# and C# using monads. He shares his code and I just stare… going WTF is this!

I know the basic concepts of what a monad is mostly due to random discussions. I never put any solid research time into what it is… why I would use it… and where does it fit into the larger scheme of my personal development toolkit.

I started my adventure in learning where I normally start… wikipedia.

http://en.wikipedia.org/wiki/Monad_%28functional_programming%29

Whoa.. lots of new terms thrown at me. Here are some random notes and crazy thoughts I am pulling out (mostly for myself).

a monad is a kind of abstract data type used to represent computations (instead of data in the domain model)

That sparks some ideas. Anyone who talks to me on a regular basis knows I am a huge Greg Young CQS fan. I think I’ve always been circling around these ideas but Greg’s insights just pulled away the haze and brought into focus the essence of what always bothered me.

For more information on Greg Young’s CQS, I would suggest http://jonathan-oliver.blogspot.com/2009/03/dddd-and-cqs-getting-started.html

Jonathan has compiled a great set of links to get introduced to the ideas. I am by no means an expert, but I consider myself a CQS disciple. :)

Back to monads.

The idea of the ‘domain’ being a ‘computation’ or ‘action’ more than data makes me think there might be a connection to explore.

Monads allow the programmer to chain actions together to build a pipeline, in which each action is decorated with additional processing rules provided by the monad.

This makes me think of the ‘reconstruction’ of a domain object by processing its events. That would be a neat POC to put together.

The return operation puts a value from a plain type into a monadic container of type M. The bind operation performs the reverse process, extracting the original value from the container and passing it to the associated next function in the pipeline.

I am still unclear on the whole wrapping business. I think I will revisit this again after going to another location to learn about monads.

So I moved over to Channel 9 and began to watch:

http://channel9.msdn.com/shows/Going+Deep/Brian-Beckman-The-Zen-of-Expressing-State-The-State-Monad/

Here are some random notes / quotes:

Only two types of variables. A bound variable and a free variable. Bound variable is a function argument. A free variable has to be looked up somewhere else.

State monad takes a state and spits out a state, content pair.

Composition is good :)

Mathematics is the art of abstraction and precision

Is functional programming and monads a disruptive technology? Although it technically isn’t that ‘new’. I think it might be. The comments around an army of OO programmers and the difficulty for learning to think functionally just resonates with the idea that functional programming is a disruptive technology (even though functional programming isn’t new).

Ok… That was a pretty rough first day. Lots of terms and pictures and strange code thrown my way. It’s time to process the information. I’m pretty sure I will need to watch that video about 5 times in-between coding this stuff. I plan on trying Brian’s exercises along with watching ‘Don’t Fear the Monad’ (another Brian Beckman presentation).

Ryan already has completed the first exercise in C# and F#. I will work on my own version of the C# exercise and then look at his code. I don’t think I will dive into F# right now. I played with the language about 2 weeks ago but all I did was create ‘Hello World’. There is a F# user group meeting on August 27th where I ‘might’ try to code these exercises.