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This is all great stuff. I’m rather meh on RBS, mainly because separating types from code is less than ideal but I like the potential here. But the right hand

This is all great stuff. I’m rather meh on RBS, mainly because separating types from code is less than ideal but I like the potential here. But the right hand assignment operator. What on earth. Nobody asked for that and nobody wants it. Why.

djur 6y ago
What's strange is that it seems to have been an offshoot of the pipeline operator (|>) work from last year[1], which was originally proposed as having an assignment syntax like foo |> bar(20) |> (x) where x is assigned to. People didn't like that syntax, and there were issues with = being higher precedence than |> [2]. This new right-assignment operator was created in response to that [3]. The weird thing is that the pipeline operator got killed, so the original reason for r-assign no longer exists. It looks to me like there's just some people on the Ruby team who took a shine to it. [1]: https://bugs.ruby-lang.org/issues/15799 https://bugs.ruby-lang.org/issues/15799 [2]: https://bugs.ruby-lang.org/issues/15799#note-22 https://bugs.ruby-lang.org/issues/15799#note-22 [3]: https://bugs.ruby-lang.org/issues/15921 https://bugs.ruby-lang.org/issues/15921
burlesona 6y ago
The examples given were all things that would be nice to do in the REPL. What I don’t understand is why not just define it in the repl, then, like ‘_’.
- jaynetics 6y ago
  Because changing or pre-processing the language syntax is far beyond the scope of any REPL. Assigning the latest return value to a variable named '_' is very straightforward and does not require dealing with the syntax.
inopinatus 6y ago
Ruby already had a sort of limited form of rightward assignment, in exception rescue: begin #... do something rescue StandardError => ex #... handle exception end The ex here can be any assignment expression, it's not just a lexical variable. So you could already do this: class Guru def meditate=(exception) puts "caught #{exception.inspect}" end end # later ... rescue OutOfCheeseError => Guru.new.meditate i.e. creating a nice opportunity for passing error handlers around as an argument; or, this worrying idea: rescue TransactionError => Thread.current[:exception] and now I'm afraid you can do this: Cat = Struct.new(:name) do class << self def all() = @all ||= Set.new def adopt=(...) all << new(...) end end end "Astrid" => Cat.adopt
- rco8786 6y ago
  Oh the error handler example is kinda cool, especially paired with inline rescues def my_method .. code .. rescue FileNotFoundError => FileNotFoundHandler rescue StandardError => StandardErrorHandler end But yea, as is so often the case with ruby, you can really shoot yourself if you try hard enough :P

djur 6y ago

What's strange is that it seems to have been an offshoot of the pipeline operator (|>) work from last year[1], which was originally proposed as having an assignment syntax like foo |> bar(20) |> (x) where x is assigned to. People didn't like that syntax, and there were issues with = being higher precedence than |> [2]. This new right-assignment operator was created in response to that [3]. The weird thing is that the pipeline operator got killed, so the original reason for r-assign no longer exists. It looks to me like there's just some people on the Ruby team who took a shine to it. [1]: https://bugs.ruby-lang.org/issues/15799 https://bugs.ruby-lang.org/issues/15799 [2]: https://bugs.ruby-lang.org/issues/15799#note-22 https://bugs.ruby-lang.org/issues/15799#note-22 [3]: https://bugs.ruby-lang.org/issues/15921 https://bugs.ruby-lang.org/issues/15921

burlesona 6y ago

The examples given were all things that would be nice to do in the REPL. What I don’t understand is why not just define it in the repl, then, like ‘_’.

jaynetics 6y ago
Because changing or pre-processing the language syntax is far beyond the scope of any REPL. Assigning the latest return value to a variable named '_' is very straightforward and does not require dealing with the syntax.

inopinatus 6y ago

Ruby already had a sort of limited form of rightward assignment, in exception rescue: begin #... do something rescue StandardError => ex #... handle exception end The ex here can be any assignment expression, it's not just a lexical variable. So you could already do this: class Guru def meditate=(exception) puts "caught #{exception.inspect}" end end # later ... rescue OutOfCheeseError => Guru.new.meditate i.e. creating a nice opportunity for passing error handlers around as an argument; or, this worrying idea: rescue TransactionError => Thread.current[:exception] and now I'm afraid you can do this: Cat = Struct.new(:name) do class << self def all() = @all ||= Set.new def adopt=(...) all << new(...) end end end "Astrid" => Cat.adopt

rco8786 6y ago
Oh the error handler example is kinda cool, especially paired with inline rescues def my_method .. code .. rescue FileNotFoundError => FileNotFoundHandler rescue StandardError => StandardErrorHandler end But yea, as is so often the case with ruby, you can really shoot yourself if you try hard enough :P