left-pad for Crystal

leftpad.cr

class String
  def leftpad(len : Int, char = ' ')
    char, len = char.to_s, len - self.size

    raise ArgumentError.new if char.size != 1

    len > 0 ? (char * len + self) : self
  end
end

p "foo".leftpad(5)    # => "  foo"
p "foobar".leftpad(8) # => "  foobar"
p "foobar".leftpad(6) # => "foobar"
p "1".leftpad(10, 0)  # => "0000000001"

@veelenga HA!