fun int[] discreteHaarWaveletTransform( int input[]){
    int sum, difference,length,i;
    int  output[input.cap()];


    for ( (input.cap() >> 1) => length ; true ;  (length >> 1) => length) {
        for (0 => i; i < length; ++i) {
            input[i * 2] + input[i * 2 + 1] => sum;
            input[i * 2] - input[i * 2 + 1] => difference;
            sum => output[i] ;
            difference => output[length + i];
        }
        if (length == 1) {
            return output;
        }

        //Swap arrays to do next iteration
        for (0=>i; i < (length<<1); i++){
            output[i] => input[i];
        }
    }
}