[lcnPylGDnU4H9OF]

> A lot of gems use exceptions for control flow

Do you happen to have an example of such control flow to link to? Not that I don't believe you but I wonder if there's a difference in what is meant by "control flow" between commenters.

  begin
    do_stuff!
  rescue MyFirstLibraryError => error
    # handle first
  rescue MySecondLibraryError => error
    # handle second
  end

That could be "control flow" to one person and "error handling" to another. Or even both to a third person.