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Merging ties

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For generating a harmonic rhythm, I needed to merge notes that are tied. If extracting only the length values with omn directly, then all ties are lost.


 (omn :length '((h c4 pizz q arco+tie) (q h tie) (h.)))
 => ((1/2 1/4) (1/4 1/2) (3/4))


So, I wrote myself a function that merges the lengths of tied notes.


 (lengths-with-merged-ties '((h c4 pizz q arco+tie) (q h tie) (h.)))
 => (1/2 1/2 5/4)



The definition is below.





(defun lengths-with-merged-ties (sequence)
  "Returns a flat list of lengths that preserves the lengths in sequence including their tied notes.
  (lengths-with-merged-ties '((h c4 pizz q arco+tie) (q h tie) (h.)))
  => (1/2 1/2 5/4)

  (omn :length '((h c4 pizz q arco+tie) (q h tie) (h.)))
  => ((1/2 1/4) (1/4 1/2) (3/4))"
   (reduce #'(lambda (&optional accum pair2)
               (when (and accum pair2)              
                  (butlast accum 2)
                  (if (equal (first (last accum)) 'tie)
                    (list (+ (first (last (butlast accum))) (first pair2)) (second pair2))
                    (list (first (last (butlast accum))) (first pair2) (second pair2)))
            (list (omn :length (flatten-omn sequence))
                  (mapcar #'(lambda (arts)
                              (when (member 'tie arts)
                          (mapcar #'disassemble-articulations 
                                  (omn :articulation (flatten-omn sequence)))))))))

;; I shared the function disassemble-articulations alongside similar functions before, 
;; but repeat it here for your convenience  
(defun disassemble-articulations (art)
  "Splits a combined OMN articulations into a list of its individual attributes.

  (disassemble-articulations 'leg+ponte)
  => (leg ponte)"  
  (mapcar #'intern (split-string (symbol-name art) :separator "+")))


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(omn-merge-ties '(q a4 stacc+tie e gliss+tie))
=> (q. a4 stacc+gliss+tie)

(omn-merge-ties '(q a4 stacc+tie e gliss))
=> (q. a4 stacc+gliss)


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nice, but didn't found this function in the library, so you has to code...

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Great, thanks! Would you consider adding a documentation file for that function? If not, could you at least add a doc string to the code, so that it could be of use for at least more advanced users?


For everyone else: when you are searching for a function that is not documented by its own RTF file and thus cannot be found via the standard Opusmodus documentation search, you could use the following function. Some internal Opusmodus functions without standard Opusmodus documentation have at least a documentation string. 


;; return all functions that contain 'omn' in their name, together with their documentation string (if there is any).

(apropos-function-documentation "omn")


The function apropos-function-documentation is defined below.





(defun apropos-function-documentation (my-string &optional (package *package*))
  "Lists all functions that contain `my-string' alongside their documentation in a list of pairs
  (<function-symbol> <doc-string>)"
  (mapcar #'(lambda (x) (list x (documentation x 'function)))
          (remove-if-not #'fboundp (apropos-list my-string package))))


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