title: Why hasn't functional programming taken over yet?
body: <p>I've read some texts about declarative/functional programming (languages), tried out Haskell as well as written one myself. From what I've seen, functional programming has several advantages over the classical imperative style:</p>
  
  <ul>
  <li>Stateless programs; No side effects</li>
  <li>Concurrency; Plays extremely nice with the rising multi-core technology</li>
  <li>Programs are usually shorter and in some cases easier to read</li>
  <li><p>Productivity goes up (example: Erlang)</p></li>
  <li><p>Imperative programming is a very old paradigm (as far as I know) and possibly not suitable for the 21st century</p></li>
  </ul>
  
  <p>Why are companies using or programs written in functional languages still so "rare"? </p>
  
  <p>Why, when looking at the advantages of functional programming, are we still using imperative programming languages?</p>
  
  <p>Maybe it was too early for it in 1990, but today?</p>