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No More Nulls Subject: Enumerated (enum) types, pattern matching, and meaningful return types. Notes Today’s episode discusses, in order: Enumerated types, with an eye to the difference between structs and enums, and to...
...It means that no one can match on your type without including sort of the underscore pattern.
Right?
They need, when they do the match,
they always need to write the code under the assumption that more things might be added.
And there are a lot of places where this...
...hello@rustacean-station.org
Timestamps & referenced resources
[@03:05] - RPIT lifetime capture rules
[@08:00] - let chains in if and while
if let temporary scope
Mara’s post on “super let”
Tail expression temporary scope
[@19:15] - Match ergonomics reservations
[@24:49] - Unsafe extern blocks
[@29:15] - Unsafe attributes...
...uh open range patterns in match statements the idea is that if you match on say an integer you can say i
want to match on zero to four and then i want to match on five and above previously you could always
match on ranges but only if they...
...And then you always have like a else match case, like what to do when none of the other matches match.
I assume you would use it with enums a lot, right?
Where you have like multiple.
Options within your enum and you essentially just want to like go through...
...And then the second argument is a pattern similar to what you
would write in any like match arm. And it just evaluates to true if the given expression matches
that pattern and to false otherwise. So it really just de-sugars to a match or like match of the...
...What does that mean, and how does it play out in Rust? We look at if and match blocks, discuss looping constructs, and examine functions, and then widen out to discuss how having an expression-oriented language can change the way we think about programming.
...Specifically, the issue is if you match on a type and in the pattern, you try to move something out of the match.
So this could be something like you match on an option or you match on a result.
And when you pattern match on OK, you try to...
...match um then it used to be that you could only really match sort of one pattern or
another pattern so you could say um let's say you're matching on uh you're matching on like an error type
like an io error and you wanted to match...
...You can either write like match, try, open thing, lots of code, close, curly, open curly, which is very awkward. And it just seems weird. You've got this match that by the time you see the arms of the match, you kind of...
...pattern matching on anything right because you can use patterns and pattern matching on not just
on emms but on structs and on tuples and on arrays and all the kind of things it lets you pattern match
on a thing and then say hey like if this match failed...
...And to not have weird like loop match
statements where you're like doing manual
state machine changes.
Someone even in the Rust subreddit today
posted something where
they're like, "Can I do this?"
And they posted some loop match.
And I'm like, "If you just use a...
...deref-coercions.html">Deref coercions Rust by Example: Flow Control: pointers/ref The Rust Reference:
...Previously, you had the choice of either matching those fields by reference, or matching them by move, right?
So if you do a match foo, then you can write the pattern as foo xy.
And then in the match arm, you can either sort of move x and y out...
...And then if let just happened because of some naive desugaring to match, to, to match, match,
as opposed to matching if I'm doing the same thing.
I was going to say you're doing the exact same thing as the headline.
Um, anyway, as far as this specific...
...2017/02/06/roadmap.html">The 2017 Rust Roadmap Improved match ergonomics around references const generics
Paths and matches and SIMD, cargo new changes, and tons of community-driven learning materials! Show Notes Rust 1.25.0 blog post
...Secret match lyrics is a variant.
Lyrics is a variant.
Comment is a variant, et cetera.
So when someone comes to me and asks me, hey, can you add support for whatever, this enum needs to change.
And this in turn is a breaking change because an exhaustive match on...
...2017/02/06/roadmap.html">The 2017 Rust Roadmap Improved match ergonomics around references const generics
impl trait, match on references, Results from main, and more. A good way to mark three years since Rust 1.0! Show Notes Rust 1.26:
"You can actually return Iterators without summoning one of the Great Old Ones now, which is pretty cool."