title: Differences between imperative and declarative programming languages?
body: <p>I know what they are:</p>
  
  <blockquote>
    <p>In an imperative programming language you tell the compiler what you want to happen step by step, whereas in a declarative language you write code which describes the result but not necessarily how to achieve the desired result. </p>
  </blockquote>
  
  <p>However, I wan't to know the optimisations of using either type of programming language. As well as this - are there any complications involved? For example the need of space/time in running a program developed in either language.</p>