If you go for Go or Rust you would never go for something like Crystal regardless, as they have different focuses. Just like Ruby, Crystal optimizes for code legibility and expressiveness, which both Go and Rust never really cared about, as it's about stability + performance (in the case of Golang) or safety + performance (in the case of Rust). Both of Go and Rust have horrible syntax compared to Ruby/Crystal, which is a fine tradeoff to make in cases.
To illustrate, when I started learning Go, I implemented Concurrent Hash Array Mapped Tries from some PhD thesis and the pseudo code algorithm actually looked pretty much like the Go code. A testament to how legible it is.
Then again, I have never tried ruby so I can't compare.
Overall I ended up writing more performance oriented applications and ruby (at least at the time) wasn't worth the 'it's pleasant to read and write' vs 'this ruby script that used to take a day now takes 15mins written in a language more suited for the task'. The other language I'd consider less expressive just in a less optimized-for-the-human-while-writing kind of way.
Crystal seemed nice in the respect that it might be the best of both worlds, but like mentioned elsewhere here it's still fairly niche.
Here's a simple example I'll do in JavaScript first since most people can read it. You have an array of the numbers 1 through 10 and want to get a new array with only the odd numbers.
arr = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
arr.filter(num => num % 2)
> [1, 3, 5, 7, 9]
arr.filter { |num| num % 2 }
=> [1, 3, 5, 7, 9]
arr.filter { |num| num.odd? }
=> [1, 3, 5, 7, 9]
We can make this even more concise though.
arr.filter(&:odd?)
=> [1, 3, 5, 7, 9]
:odd? is a Symbol
The & operator calls the #to_proc method on the symbol :odd? then converts the result into a block, which is passed to the filter method. In other words, the #odd? method is called on each element in the array no different than the previous example.
Here's another way to express the exact same thing:
arr.reject(&:even?)
=> [1, 3, 5, 7, 9]
Another one of my favorite language features is that parentheses on method calls are optional, so a lot of syntax that looks like it would be language-level operators are actually just regular method calls to objects in Ruby. An example of this is ==, which is an operator in many other languages. In Ruby it is a method call. Consider this expression:
true == false
true.==(false)
Pseudo-code, but this is how I see the difference in expressiveness and syntax:
3.times {
println('Foobar')
}
for i in 0..3 {
println!("Foobar")
}
> because it's a huge hindrance to trying a large number of languages out there with lots of nice things
I know exactly what you're talking about, as most of the time I work in Clojure, and trying to show Clojure to other programmers who are used to C-like languages and never heard of any lisp-like language is a constant struggle, as their first reaction is always "eww, parenthesizes everywhere!" even though their favorite language usually has the same amount or even more.
It's certainly a taste thing, but I am not enjoying it at all. I find it unpleasant. I think it's going to join the short list of "languages I can use but would prefer not to".
I've never learned Crystal, but if it's like Ruby, then I think I'd enjoy it just fine.
It retains most of the flexibility and DSL capabilities, but the type- and nil-safety allow you to leverage them without nasty surprises at runtime.
Not having to guess what a method or block returns and instead having the compiler tell you when you get it wrong makes an enormous difference.