The Crystal programming language | http://crystal-lang.org | Fund Crystal's development: http://is.gd/X7PRtI | Docs: http://crystal-lang.org/docs/ | API: http://crystal-lang.org/api/
<straight-shoota> *kotlin
<raz> https://kotlinlang.org/docs/null-safety.html#the-operator - similar to crystal but syntax is more convenient, closer to ruby in that regard (
?. instead of .try &)
<raz> (eh sorry, my link hit a bit too low, you gotta scroll up a bit to "Safe calls")
<straight-shoota> An equivalent alternative to
if foo = some_nilable would be foo = some_nilable; if foo (or maybe a dedicated assignment operator as @asterite mentioned)
<raz> (as mentioned in kotlin
if foo = anything is not allowed at all. i imagine they may have had a similar discussion in their past)
<straight-shoota> Hm, I've never used
if foo = nilable instead of foo.try {}
<raz> when it's followed by a longer block, or worse, when the var is then used outside of that block, it can be quite confusing
<xyhuvud> you don't get to avoid it for @instance variables anyhow, so you might as well embrace it.
<straight-shoota> TIL *_with_index is not limited to integer index
<straight-shoota> >> (0..4).each_with_index('a') { |x, i| puts "#{i}: #{x}" }
<DeBot_> straight-shoota: a: 0 - more at https://carc.in/#/r/blo8
<straight-shoota> printing ordered lists (like
list-style-type: lower-alpha in CSS)
<raz> that might get a bit nasty after 25 items ;P
<straight-shoota> replacing
i += 1 by i = i.succ makes it even more generically useful
<straight-shoota> all good with succ + String: https://carc.in/#/r/blod
I tried
brew install crystal and with --build-from-source
I am not that familiar with generics in Crystal, and I'm wondering if they are similar to Nim or Rust in that I can restrict a generic type parameter inline. The following is a Nim function definition, where
T is restricted to be of type Vec, which is used for both arguments and the return type. How can I do similar with Crystal, without a type alias or relying on the inferred call site types?proc abs[T: Vec](o: var T, v: T): var T = ...
i.e. not something the lang supports atm
<straight-shoota> This would be an example of a macro-based type restriction: https://github.com/crystal-lang/crystal/blob/13dd77ef01c0d55f2d43372f97c648ff81c737d9/src/slice.cr#L745-L748
Yeah I'm not a fan of making the body less readable to restrict a type or two
Also not realy a fan of Nim's inline restriction...would like a more readable
where or even overloading forall
I think I want to see the information in the
signature where it belongs
so :shrug: could be worse
:) Sure, not a deal breaker for me. I like Crystal's "for humans" philosophy, and adding line noise is not in line with that :)
Regardless, it is one thing I would use a lot if it was a thing.
I might play around with a macro sometime...for now it's not really needed. Thanks!
I thought about your macro generating the entire
def instead of mine just generating the body, and I decided on mine, for a couple reasons. 1) The readability as mentioned. 2) I would like to selectively choose which ones to annotate as always inlined, 3) I would like to add additional logic to some methods.
I'm trying to write a class method that initializes an Indexable type with random floats.
def self.rand(min = 0.0, max = 1.0)
res = new
res.each_index { |i| res[i] = Random.rand min..max }
res
endThis works, but I am wondering if this can be done more concisely/in one line instead of 3. Don't really want to macro around this if the language has something I could use that I don't know about.