alt Hacker News> `a -> a`; `[a] -> [a]`; It means nothing! It tells you nothing!
— Rich Hickey, Effective Programs[0]
[0]: https://www.youtube.com/watch?v=2V1FtfBDsLU&t=4020s
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A disastrously poor take. I used to work at a Clojure company, and there's no chance I'd ever go back to that.
Replies
I worked for a startup that used clojure and found it so frustrating because, following the idiomatic style, pathways passed maps around, added keys to maps, etc. For any definition which received some such map, you had to read the whole pathway to understand what was expected to be in it (and therefore how you could call it, modify it, etc).
I think the thing is that yes, `[a] -> [a]` tells you relatively little about the particular relationship between lists that the function achieves, but in other languages such a signature tells you _everything_ about:
- what you need to call invoke it
- what the implementation can assume about its argument
i.e. how to use or change the function is much clearer
I used to work in a Clojure company, but you wouldn't believe how loudly the lead developer chewed when we had lunch, never Clojure again after that.