Why Functional Programming Matters (1984) [pdf]
A lot of pleas for functional programming give a long list of convincing examples that work well with functional programming. You can do this with almost any language, and this is also quite deceptional, as this is often done to convince beginners to learn another language; &quot;look at how simple it is to program this contrived example in &lt;language X&gt;!&quot;.<p>In order to be able to use a programming language or paradigm well, it is especially useful to know what its weaknesses are. Functional programming does not work well in programs which handle a lot of states. It does not work well in programs which have high requirements for performance or memory. It does not work well for programs which have to do low-level stuff.<p>These are serious disadvantages, and I would like to see them highlighted more often in this introductory-style articles. Nevertheless, I think functional programming is a must to be able to write simpler programs, and I think programmers should write functions (i.e. methods that only depend on their arguments) whenever possible, for modularity and correctness reasons. I think the disadvantages can be solved by non-pure functional languages, and that there is a lot to gain for new programming languages in this area.