Functional Programming Lessons Conclusion

Summary

As many others observe as well, one of the major reasons to write is to firm up ideas in one’s own head. Serializing an idea out into English words is still no guarantee one understands it deeply, but it is great progress over a very fuzzy idea that has never been fleshed out at all. I’ve known for a long time I wanted to sit down and write this out. But I had no idea how many principles I’ve either drawn out from my times with functional languages, or had sharpened by them forcing me on to certain paths that perhaps I would have walked eventually, in bits and pieces, but functional programming forced upon me in toto. And it wasn’t until I’d written several of these posts that I noticed the recurring theme of scale, that functional programming principles are best brought in to imperative languages at the medium scale rather than the micro scale. I find this insight to have been almost worth the writing on its own. I arranged these points roughly in order from least offensive to most offensive, so it’s possible that you arrive here thinking I do not like functional programming. But consider how much I have drawn from it. This is a good thing. I like it. What I do not like is what I consider the surface level application of the lessons of functional programming. I do not like people obsessing about the micro-scale of functional programming, often to the point they actually harm their own code bases, while at the same time writing higher-level structures indistinguishable from the rest of the imperative world. If all you’ve done is walk through your program and change all your for loops into maps and reduces, but your high-level architecture is still a confused mess with no discernable boundaries or structure… at best you’re got a marginal gain, and most likely, you’ve taken a step backwards! If you are lucky enough to work in a domain where you can use high-end functional programming languages, by all means, adopt the relevant idioms wholesale. But if you are not, I e...