anchor.diff:  ;; => (4 5 6 5 6 7)
   ----
   
  +
   ==== Set
   
   Sets implement almost every abstraction in _cats_, from Semigroup to Monad.
  
positive.code: 
  Also, since `mlet` desugars into calls to the Monad's `bind` function, its result keeps the type of the monadic values.
  
  ==== Lazy sequences
  
  Lazy sequences implement the same abstractions as vectors with practically an identical implementation. If you don't need
  
negative.code: [cats "0.4.0"]
  ----
  
  
  === Get the Code
  
  _cats_ is open source and can be found on link:https://github.com/funcool/cats[github].
  