Cupid is a brainfuck derivative.
There are nine commands which are processed in two-character sequences. The command sequences are formed by using characters '<', '>', and '-'. Only difference, or rather, addition to brainfuck is that in Cupid it's possible to output the current state of the storage tape.
>> input a byte to current cell << output the current cell as character -> move memory pointer one right <- move memory pointer one left >< increase the current cell <> decrease the current cell -< if the current cell is zero, jump to the corresponding >-, otherwise continue >- jump back to the corresponding -< -- output the current state of the storage tape