The build file "cmn-all.lisp" is broken.
I've managed to patch it, the following builds but I haven't tested if
the result works properly.

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(define-public sbcl-cmn
  (package
    (name "sbcl-cmn")
    (version "2016.8.17")
    (source
     (origin
       (method url-fetch)
       (uri (string-append "https://ccrma.stanford.edu/software/cmn/cmn"
                           ".tar.gz"))
       (sha256
        (base32
         "1f4ivhg1vq2fwklmwjj30bj7ij1yab45rnjjwps3qpsh0lpd6yj3"))
       (file-name (string-append name "-" version))))
    (build-system asdf-build-system/sbcl)
    (arguments
     `(#:phases
       (modify-phases %standard-phases
         (add-after 'unpack 'fix-build
           (lambda _
             (substitute* "cmn-all.lisp"
               (("\\(setf cmn::\\*cmn-binary-directory\\* \\(namestring \\(truename cmn-bin-directory\\)\\)\\)")
                "")
               (("\\(setf cmn::\\*cmn-source-directory\\* \\(namestring \\(truename cmn-directory\\)\\)\\)")
                "")
               (("\\(cmn-compile-and-load file\\)")
                "(load (asdf:system-relative-pathname :cmn file :type \"lisp\"))")))))))
    (home-page "https://ccrma.stanford.edu/software/cmn/")
    (synopsis "Western music notation package written in Common Lisp")
    (description
     "CMN provides a package of functions to hierarchically describe a musical
	score. When evaluated, the musical score is rendered to an image.")
    (license license:llgpl)))
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