Functional programming considered harmful
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I happen to have a strong background in mathematics but also a keen interest in quirky theorems, properties and proofs – and I find functional programming entertaining. It’s an easy (and natural?) way to solve certain problems. With that being said, I believe that functional programming is not appropriate for large companies and in general for most use cases.
As your company grows, the truth is that your bar will eventually lower – you can’t have a company with a thousand engineers where all of them are staff engineers. From there, code has to be readable and maintainable by everyone in the company – so code has to be simple. Functional programming is fine in easy cases (e.g. seq.filter(x => x > 2)) but isn’t adequate when things get more complex.
Two practical issues I have with functional programming that aren’t about code esthetics or readability of the code itself (as these might be personal preferences):
- Stacktraces are less readable in case of errors compared to their equivalent with imperative programming – they are longer and may end up truncated.
- You may end up with stackoverflow errors – this is especially problematic if the depth of your recursion depends on user input. You basically have a DDOS vulnerability in your system.
Functional programming is akin to object oriented programming – they are good ways to write code in some cases, but you shouldn’t force them when they aren’t adequate.