There have been several times over the last few weeks when I’ve wanted to reverse small strings, mostly for nicer printf-debugging. Was a reverse function ever part stdlib/pervasives at some point and removed for some reason or the other? Base, containers, and batteries all have it in their string …

[image] c-cube: Correct me if I’m wrong, but even python will reverse the order of codepoints, not grapheme clusters or whatever the actually useful notion of character is. You are right. For example, the accent gets moved to the other letter on the following example. (Hopefully, Discourse do…

Overall, we’ve haven’t reached the kind of support for String.rev that I was hoping for, so I think we can put this to rest. Probably didn’t help that there’s a separate heated Stdlib conversation happening. If you find a good use for String.rev feel free to revive this thread. I’ll summarize the di…

[image] ifazk: quick hacks to check for palindromes You don’t want to create the reversed string for that. [image] ifazk: printing bytes in reverse order for debugging You also don’t want to create the reversed string to just iterate the string in reverse order. Note that those two u…

[image] octachron: far from ideal since char list is really inefficient Yes, but it is a one-liner where you don’t have to worry about indexes. Useful for quick-hack situations, e.g. in a REPL or when you’re going to delete the code later anyway.

Thanks @ifazk for taking the time to write a summary! That will constitute a good starting point, should the question be raised again. [image] ifazk: A second objection to String.rev is that it’s not meaningful if your bytes represent Unicode code-points. Unicode is honestly too messy, and I am…

[image] ifazk: String.get (len - n - 1) x it shoud be the other way around: String.get x (len - n - 1)

Thanks, I’ve fixed it in my posts.

Out of curiosity/fun (or stupidity? I have absolutely no use of this function!)… I tried a dozen of implementations and benchmarked them for speed. The clear winner for me (ocaml 4.13.0, linux) is the following let rev3_unsafe x = let len = String.length x in let y = Bytes.of_string x in for…

Interesting, I wonder if my go-to implementation using Bytes.create makes a difference at all. let rev s = let b = Bytes.unsafe_of_string s in let len = Bytes.length b in let b1 = Bytes.create len in let rec loop n = if n = len then Bytes.unsafe_to_string b1 else let nex…

Should we have a `String.rev` in `Stdlib`?

Ecosystem

sanette January 22, 2022, 11:02am 20

it shoud be the other way around:
String.get x (len - n - 1)

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Should we have a `String.rev` in `Stdlib`?

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