Redo a loop iteration

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1

Unlike Ruby, Crystal seems to lack the redo statement. Do you think it would be useful to write code like this?

some_items.each do |item|
  case process(item)
  when "foo" then true
  when "bar" then false
  else redo
  end
end
2

Am I missunderstanding something, or would “redo” do exactly just lead to an endless loop here?

Because if the item doesn’t fit the first time, why would it fit the second time?

3

The value which is returned by process(item) can change with time, so it’s not necessary an endless loop.

4

ahh, i see. You could just “redo” inside process(item) and only return when its done?

But I see the general idea.

5

Yes, it could be that way (the example is not the best one). And it’s possible to overcome the lack of redo, but the code becomes unnecessary bulky, IMO.

6

Yeah, it’s a deliberate choice because I never used it in Ruby, nor my peers. It could be done but since its use case is so limited and there are ways to do it without a language keyword we will probably never incorporate it in the language (though now that I think about it, it’s just a jump to the beginning of the iteration, but there will be new typing rules).

7

It’s just one more loop:

some_items.each do |item|
  loop do
    case process(item)
    when "foo" then break true
    when "bar" then break false
    end
  end
end
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