Comment #1 on issue 3098 by [email protected]: Parser diagnostics failing to recognise \on-the-fly arguments as procedure type
http://code.google.com/p/lilypond/issues/detail?id=3098
#first-page is executed in lexical closure. Its meaning depends on the meaning of first-page at the place #{ ... #} is executed. So you either need to bring first-page into lexical reach at the point of calling #{ ... #}, or you need to write \first-page instead which does _not_ use lexical closure.
