Ruby Redo

Ruby has a keyword redo that you might see inside a block. It causes the unconditional re-execution of the block, with the same parameter bindings as the current execution.

Here it is, causing an endless loop:

n = 0
until n == 1 do
  puts n
  n += 1
  redo
end

redo does not evaluate the 'until' condition, so the likelihood of it causing an endless loop is high.

I'd love to see a practical application. It seems to me that redo would have to be inside a conditional, based on some information coming from outside the loop-- information we are certain will eventually be false.

That's a lot to ask; I would avoid redo in most cases.