Comment by usrusr | Hacker News Reader

Comment by usrusr | Hacker News Reader

Parent Full thread

Why would you ever want the dotless version though, in cases where it's not terrible? (e.g when there are multiple arguments of equal importance and calls where the argument is appears more as an option for esoteric cases than the implementation's main subject)

I really like the option to "semantically scope" a function to its main subject, like in kotlin extension methods. But I fail to see why I'd ever want to have both options. Is it just a compatibility thing, to be able to call code written for conventional languages? Or from developers who don't like that approach?

Here's one case. Instead of

  let letters = word.chars().filter(|ch| ch.is_alphabetic());

you can just write

  let letters = word.chars().filter(is_alphabetic);

since the difference between "methods" and "functions" is purely syntactic.

Most languages that have a way to define dot-syntax functions that aren't actually methods of the type also come with the ability to use any zero-arg method (both true methods and dot-syntax extension functions) as a one-arg function reference, or rather n-arg methods as n+1-arg function references. No need to crowd the unqualified namespace just to be able to use them without wrapping in a lambda.

Reply on news.ycombinator.com