templates palindrome
  [$...] -> #
  when <=$(last..first:-1)> do '$...;' !
end palindrome

test 'palindrome filter'
  assert 'rotor' -> palindrome <='rotor'> 'rotor is a palindrome'
  assert ['rosetta' -> palindrome] <=[]> 'rosetta is not a palindrome'
end 'palindrome filter'