Issue 3560: Completion_heads_engraver with \scaleDurations

scm/c++.scm

 ;;;; This file is part of LilyPond, the GNU music typesetter.
 ;;;;
 ;;;; Copyright (C) 1998--2012 Jan Nieuwenhuizen <janneke@gnu.org>
 ;;;;                 Han-Wen Nienhuys <hanwen@xs4all.nl>
 ;;;;
 ;;;; LilyPond is free software: you can redistribute it and/or modify
 ;;;; it under the terms of the GNU General Public License as published by
 ;;;; the Free Software Foundation, either version 3 of the License, or
 ;;;; (at your option) any later version.
 ;;;;
@@ skipping 14 matching lines @@
   (and (pair? x)
        (number? (car x)) (number? (cdr x))))
 
 (define-public (number-pair-list? x)
   (and (list? x)
        (every number-pair? x)))
 
 (define-public (fraction? x)
   (and (pair? x)
        (index? (car x)) (index? (cdr x))))
+
+(define-public (rational-or-procedure? x)
+  (or
+   (and (rational? x) (exact? x))
+   (procedure? x)))
 
 (define-public (number-or-grob? x)
   (or (ly:grob? x) (number? x)))
 
 (define-public (grob-list? x)
   (list? x))
 
 (define-public (number-list? x)
   (and (list? x) (every number? x)))
 
@@ skipping 65 matching lines @@
 
 (define-public (object-type-name obj)
   (type-name (match-predicate obj type-p-name-alist)))
 
 (define-public (type-name predicate)
   (let ((entry (assoc predicate type-p-name-alist)))
     (if (pair? entry) (cdr entry)
         (string-trim-right
          (symbol->string (procedure-name predicate))
          #\?))))