soundon

;; build the harmony argument for four frequencies
to fourpart :basefreq 
  local [a]
  make "a []
  make "a fput list basefreq     [[.9 50] [0 450]] a 
  make "a fput list basefreq*2   [[.9 50] [0 450]] a 
  make "a fput list basefreq*0.5 [[.9 50] [0 450]] a 
  make "a fput list basefreq*3/2 [[.9 50] [0 450]] a 
  output a
end


;; here's a mapping function of the sort found in many functional
;; languages.  an anonymous function is applied to list element by
;; element. 
to mapping :f.template :template.list
        ifelse (empty? :template.list) [
          output []
        ] [
          output (fput (apply :f.template (list (first :template.list))) ~
                     (mapping :f.template (butfirst template.list)))
        ]
end


;; here's a modified map function.  the anonymous function is again
;; applied to each element in the list.  however, nothing is returned
;; since the output of anonymous function has been sent to the sound 
;; card. 
to sing :f.template :template.list
        ifelse (empty? :template.list) [  ] ~
        [ apply :f.template (list (first :template.list))
          sing :f.template (butfirst template.list) ]
end


;; define a list of frequencies
make "notes [440 494 554 587 659 739 830 880]


;; now put it altoghter
sing [harmony fourpart ?] notes