Tackling Workflows

"Workflows" are everywhere in business software. It's usually everything after the POST in a web app. It's where the business's secret sauce happens. It's all that stuff that project managers write up with flowcharts or intricate prose (that is if it's written up at all!). In short, it's all that doing stuff that has to get done. How do we work with that in Haskell?

Simon Peyton-Jones once quipped1:

> In short, Haskell is the world’s finest imperative programming language.

WTF!? I thought Haskell was the opposite of imperative programming. Well, I want to convince you that Haskell's treatment of imperative code as values actually makes the above statement more true than you may think.