Slice patterns in Nightly Rust

QAston via Digitalmars-d digitalmars-d at puremagic.com
Sun Jun 21 02:39:18 PDT 2015


On Sunday, 21 June 2015 at 03:23:18 UTC, Dennis Ritchie wrote:
> Recently published documentation Nightly Rust. I saw this:
> https://doc.rust-lang.org/nightly/book/slice-patterns.html
>
> What do you think about this: a terrible thing or a cool 
> feature?
>
> fn is_symmetric(list: &[u32]) -> bool {
>     match list {
>         [] | [_] => true,
>         [x, inside.., y] if x == y => is_symmetric(inside),
>         _ => false
>     }
> }
>
> fn main() {
>     let sym = &[0, 1, 4, 2, 4, 1, 0];
>     assert!(is_symmetric(sym));
>
>     let not_sym = &[0, 1, 7, 2, 4, 1, 0];
>     assert!(!is_symmetric(not_sym));
> }
>
> http://is.gd/TvrXSn
>
> I see this competition slices of D. Also seen are not very 
> clear design.

Like, every modern language has a notion of closed iteration 
abstraction (Ranges, Java streams, Clojure seqs, .net LINQ, 
etc...). Many also have slicing: go, python, rust, ml...

It's time to get over thinking those are unique :)

What you linked here is a tutorial for pattern matchig on slices 
(which is a feature unrelated to D as it doesn't have pattern 
matching)- the doc for slices themselves is here:

http://doc.rust-lang.org/nightly/std/slice/


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