title: Combination monads in F#
body: <p>I'm trying to get my head around monads in F#, and am looking for an example of composing them.</p>
  
  <p>In haskell it looks like you would use Monad Transformers but in F# it appears that you would create your own computation expression builder.</p>
  
  <p>I can get behind that, but are there any examples of some combinations of the standard monads and how to use them?</p>
  
  <p>I'm particularly interested in combining Reader, Writer and Either to build functions that take in an environment, tweak it, and then using Writer return the changes to the environment that took place.  Either would be used to differentiate between successes and failures.</p>
  
  <p>For now, it would be great to obtain a example of an EitherWriter computation expression which produces a value+log or an error.</p>