:mkchordbystep   scheme

; 
; :MKCHORDBYSTEP // 1-based (= tonic)
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
; Returns a chord based on steps of a scale. Eg (:mkchordbystep 60 '(1 3 5) 'ionian  ) ; => tonic chord ie (60 64 67)
; Optional args are: relative pitch (default: none) 
; To determine the scale, accepts either a scale/mode (defaults ionian) or a M/m symbol. 
; When a relative pitch is passed, the steps calculation begins from that pitch (if it exists in the scale)
;
; Examples:
; (:mkchordbystep c4 '(1 3) 'M  ) ; => (60 64)
; (:mkchordbystep 60 '(1 3 7) 'ionian  ) ; => (60 64 71)
; (:mkchordbystep 60 '(1 3 7) 'ionian 62) ; => (62 65 72)  / start from D, in C Major
; (:mkchordbystep 60 '(1 3 7) 'ionian 73) ; => (74 77 84)  / quantize 73 to 74 cause it's not in scale
;
; See also
; (pc:melody-by-step 60 '(0 2) '(0 4 7)) ;=>'(60 60 67) 
;
(define :mkchordbystep
  (lambda (seed steps scale . args)
  ; (println args)
   (cond ((null? args) ;; default
          (takel steps (:mkscale seed scale *default_scale_len* )))      
          ;
          ((length-equal? args 1) 
            ;; 1 arg: relative pitch 
            ;; EG in C-major, D => starting from D, take 1, 3, 5
            (let ((sc (:mkscale seed scale *default_scale_len* ))) 
                ; (println (list-split-from (cadr args) sc)) 
                (if (member (car args) sc) 
                    (takel steps (list-split-from (car args) sc))
                    (begin 
                      (log-info "Error: Pitch not in scale. Quantizing..")
                      (takel steps (list-split-from (mkquant (car args) sc) sc)))
                )))  
          ;
          (else (print 'Error: 'arguments 'could 'not 'be 'resolved.))              
      )
    )          
)