Written April 17, 2013 updated: May 20, 2013 Here's a simple value: And we know how to apply a function to this value: Simple enough. Lets extend this by saying that any value can be in a context. For now you can think of a context as a box that you can put a value in: Now when you apply a function to this value, you'll get different results depending on the context. This is the idea that Functors