Super fast recursive Fibonacci implementation in Haskell

The Fibonacci sequence is a classical hello-world application for functional programming. The challenge here is to get a fast implementation. We will first show two classical implementations: the trivial recursive definition that is very slow and the iterative version that is slightly faster.

And a third one that is blazing fast.

So here is my own version...

• the source code in Literate Haskell: fibonacci.lhs
• the document rendered in Markdown: fibonacci.md