I had wondered why most recent Ruby releases were on Christmas Day and recently found out why. The Ruby creator Matz is religious (LDS), and he considers it a Christmas gift to the community. I thought that was really cool.
One of the interesting news is that they are now going to start requiring a C99 compiler, instead of only C90.
I've been considering to do the same on my own projects. What does HN have to say about this? Is anyone here still working in a context where C99 is not an option? Did anyone else also recently switch to C99? How did it go?
It's now 2019, and as far as I know, MSVC still doesn't have full support for the 20-year-old C99 standard.
So either you restrict yourself to the subset of C99 which MSVC understands (AFAIK, newer MSVC releases understand more and more of the C99 standard), or just decide MSVC is no longer relevant (which is easier now that clang-cl exists; some big projects like Firefox and Chrome went this way, see for instance https://blog.mozilla.org/nfroyd/2019/04/25/an-unexpected-ben...).
Mostly portable implementations of extensions for me; __thread, bool, inttypes.h, variadic macros, flexible array members etc. But declaring variables closer to the point of use is nice, as is struct initializers, compound literals and single line comments.
Compared to the rest, C99 contains a lot of useful improvements.
Funny thing: I always bring up how Ruby has private methods while Python doesn't, when toying around with colleagues about languages, etc. well there goes that I guess.
Sidenote: I can't think of a use case where this is a good idea.
You've been able to use `send` to pierce the protected/private restriction forever, so this doesn't particularly change the nature of Ruby's method visibility rules. Now you can just use `self.foo` and it's the same as `self.send :foo`.
class Foo
def test
priv # works
self.send(:priv) # works
self.priv # doesn't work under ruby 2.6-
Foo.new.priv # doesn't work
end
private
def priv
puts "ran private"
end
end
You shouldn't typically need to be using `self` at all, except when it's clarifying or disambiguating, so you shouldn't generally run into that issue. On occasion, though, you add a `self.` prefix to a method call and can break code that was otherwise working, because you've subjected your code to a scope protection that it wasn't subject to before.
> You've been able to use `send` to pierce the protected/private restriction forever, so this doesn't particularly change the nature of Ruby's method visibility rules.
I know it's slow at the moment, but is anyone planning on using pattern matching for anything in particular? Curious what use cases are particularly suitable for it.
I’d love to, if it helps with things like Either/Maybe types. Although from what I’ve looked at briefly the syntax felt a little less intuitive than I’ve seen in other languages.
Maybe I’ve just been bitten by the functional bug but I find they can communicate intent much better than scattering around null checks or catching exceptions (many of which require reading the source to understand what exceptions you might get).
It’s great in large scale projects, which I think is where a dynamic language starts to show its warts.
Given that we're talking about it in a pattern matching context, you'd just pattern match on x vs nil, rather than matching on Just x or None. And in case of Either, you'd match on the types that you expect.
An alternative to scattering null checks around or using exceptions for control flow could be more thoughtfully designing your data/object model. No additional language constructs required!
That attitude is the source of billions of dollars in bugs...
Never manually do the work that the compiler / runtime could do.
You can design "more thoughtfully designing your data/object model" (in other regards) AND have the compiler make sure you're not doing null referencing for you (so that that's not your concern anymore) -- instead of manually and in an ad-hoc way per project implementing another menial responsibility into the design of your model.
Yeah I suppose my bigger beef is I just don't like dynamic languages. Perhaps it is in fact a good idea for them, but being someone primarily interested in types, it largely falls into the realm of "don't care."
The idea of Maybe is that you usually don't check for None. The idea is that you use it sort of like a collection in most cases, allowing the None to propagate up as the result of collection operations on other Nones. The issue can be that you get a None at the end and it isn't clear where it came from originally, and how it reached you. Adding stack trace information to each intermediate None, when in debug mode, can help you trace what went wrong.
I was introduced to it in Scala. I like how all "classic" languages are cherry-picking features from functional programming. It will make people less shell-shocked in the future, when they try it for real.
Yup, Scala, F#/OCaml and Rust have the best pattern matching implementations I've seen. I'm happy to see other languages slowly coming around. Java has a JEP for it (although nowhere near as nice as Scala's). Even JavaScript has a TC-39 proposal, although its champion has gone on to focus more on Rust. I'm excited for the future.
Basically this is Elixir's case, so a very narrow instance of what Elixir's pattern matching is. I'd love to see more pattern matching added to Ruby year after year. However adding everything Elixir has probably would require a total rework of the language. Example: multiple method definitions, one per pattern.
I wonder what's going to be the idiomatic way to handle a failed match. Elixir ends the process but there is likely a supervisor to restart it. In the case of Ruby the process ends and there is nothing to restart it. In the case of Rails I expect the web request to fail with a 500 and maybe the next one will get more luck.
The compaction GC was the most important change. I haven't measured Ruby's performance specifically but in general the difference and improvements over a non-compacting GC is so huge. Specially for long running processes.
Its an important change, but not huge, at least not yet: it's not yet integrated in the GC, which means you have to explicitly request it. And most of the fragmentation comes anyway from the allocations heap. That being said, I think this will improve in the coming releases.
What criteria should be monitored to request compaction in a long-running process? Is a timer sufficient (at what interval?) or are there other tools available in Ruby to make that decision?
It's likely to be most useful for anyone using a Unicorn-style process forking model in Ruby.
You call `GC.compact` in the parent right before forking off your child processes and because the memory in the children are copy-on-write (COW), it lets them share memory with their parent far longer than they normally would be able to.
Any change in a page (i.e. an object allocated or deallocated) causes it to be copied to a child process, and because previously pages were a mix of objects of all kinds of longevity and slots which may be empty or used, children tended to copy their parent's entire memory space very quickly. Running a GC and compact before forks improves the likelihood that shared pages are mostly full of still-in-use, longer-lived objects, and gives the COW strategy a fighting chance.
Yes in other languages, but as far as I am aware that is not the case in Ruby ( Specific to Rails ) . At least I wouldn't use so huge to describe the improvement.
I stumbled across collections.Counter during last year's Advent of Code, and promptly kicked myself for the number of times I'd implmeented that by hand.
Does the pattern matching do something that Ruby's map() can't do?
Coming from Perl, map() there can return fewer elements than the source list, so pattern matching works already. A short skim of Ruby's map seems to imply it always returns something with the same number of elements.
Edit: I was confused about what this feature did. So this subthread is still interesting, but mostly unrelated.
Yeah afaik something is always returned from the block (even if it’s nil). Occasionally I recall my self doing something where the block might return nil and then I’d call `compact` to get rid of extra nil stuff. It works when you want a modified version of the enumerable but don’t want nil stuff. If you just want to match a subset then I think `select` is probably what you want.
Further, the pattern matching feature is significantly different than `map` imo.