scheme'n'bass

[Jason Levine]

Hi Extempore, 

I think I found a solution to my drum'n'bass idea using only functions, but I'm having a little trouble with one function. (and I started a new thread because I am no longer talking about macros)

Basically, one way of thinking of drum'n'bass beats is as a concatenation of rhythmic fragments.  

I'm representing each fragment with a list that will become part of set to be played by ```playobs```

so if I concatenate this fragment ```'(0 1/2)``` with this fragment ```'(0 1/4)```  I want to get a temporal recursion like this: 

```(define playloop

  (lambda (beat dur)

    (playobs (list 0 1/2 2/2 5/4) 2 drums 10 80 dur)

    (callback (*metro* (+ beat (* .5 dur))) 'playloop (+ beat dur) dur)))

(playloop (*metro* 'get-beat 4) 1/4)```

so I created two functions to do the first part of this:  

```(define inc-frag

  (lambda (frag inc)

   (if (null? frag) 

       '()  

       (cons (+ (car frag) inc) 

             (inc-frag (cdr frag) inc)))))

(define assemble-frags

  (lambda (frags inc)

   (if (null? frags) 

       '()

       (cons (inc-frag (car frags) inc) 

             (assemble-frags (cdr frags) (+ inc 1))))))```

so ```(assemble-frags ('(0 1/2) '(0 1/2) '(0 1/4)) 0)```  should return the set ```'(0 1/2 2/2 3/2 4/2 9/4)```

inc-frag gives the correct results, but assemble-frags only returns the last element of the input list (0 1/4)  and seems to set extempore into an infinite loop.

The function seems to make sense, but when I  change the null condition from '() to '(1) I still get (0 1/4) as an answer, which makes me wonder if the function ever makes it to the null condition.  But if not, how does it return anything at all? Next I tried,

```(define assemble-frags

  (lambda (frags inc)

   (if (null? frags) 

       '()

       (begin (cons (inc-frag (car frags) inc) 

             (assemble-frags (cdr frags) (+ inc 1)))

             (println "test")))))```

And still, I only get (0 1/4) in the console.

 Anyone have an idea what I'm doing wrong?

Thanks!

Jason