The error message is rather flowery:

;;; note: source file /tmp/bug13.scm
;;;       newer than compiled /usr/local/tmp/guile/cache/guile/ccache/2.2-LE-4-3.6/tmp/bug13.scm.go
;;; note: auto-compilation is enabled, set GUILE_AUTO_COMPILE=0
;;;       or pass the --no-auto-compile argument to disable.
;;; compiling /tmp/bug13.scm
;;; WARNING: compilation of /tmp/bug13.scm failed:
;;; ERROR: Syntax error:
;;; /tmp/bug13.scm:2:0: source expression failed to match any pattern in form (define (styled-metronome-markup #:optional (glyph-font (quote default))) (lambda* (event context) "What a mess"))
ice-9/psyntax.scm:1081:18: In procedure #(#(#(#<variable 996aff0 value: #<procedure 996c980 at ice-9/psyntax.scm:288:10 ()>> #(#<procedure expand-sequence (body r w s mod)> #-1# (#<variable 996afe8 value: #<fluid 14>> . #<variable 996aff0 value: #<procedure 996c980 at ice-9/psyntax.scm:288:10 ()>>)) (#<variable 996afe8 value: #<fluid 14>> . #<variable 996aff0 value: #<procedure 996c980 at ice-9/psyntax.scm:288:10 ()>>)) #<variable 996aff0 value: #<procedure 996c980 at ice-9/psyntax.scm:288:10 ()>> (#<variable 996afe8 value: #<fluid 14>> . #<variable 996aff0 value: #<procedure 996c980 at ice-9/psyntax.scm:288:10 ()>>) #(#<procedure expand-sequence (body r w s mod)> #(#<variable 996aff0 value: #<procedure 996c980 at ice-9/psyntax.scm:288:10 ()>> #-1# (#<variable 996afe8 value: #<fluid 14>> . #<variable 996aff0 value: #<procedure 996c980 at ice-9/psyntax.scm:288:10 ()>>)) (#<variable 996afe8 value: #<fluid 14>> . #<variable 996aff0 value: #<procedure 996c980 at ice-9/psyntax.scm:288:10 ()>>))) #(#<variable 996aff0 value: #<procedure 996c980 at ice-9/psyntax.scm:288:10 ()>> #(#<procedure expand-sequence (body r w s mod)> #-1# (#<variable 996afe8 value: #<fluid 14>> . #<variable 996aff0 value: #<procedure 996c980 at ice-9/psyntax.scm:288:10 ()>>)) (#<variable 996afe8 value: #<fluid 14>> . #<variable 996aff0 value: #<procedure 996c980 at ice-9/psyntax.scm:288:10 ()>>)) #<variable 996aff0 value: #<procedure 996c980 at ice-9/psyntax.scm:288:10 ()>> #(ribcage () () ()) (#<variable 996afe8 value: #<fluid 14>> . #<variable 996aff0 value: #<procedure 996c980 at ice-9/psyntax.scm:288:10 ()>>) #(#<procedure expand-sequence (body r w s mod)> #(#<variable 996aff0 value: #<procedure 996c980 at ice-9/psyntax.scm:288:10 ()>> #-1# (#<variable 996afe8 value: #<fluid 14>> . #<variable 996aff0 value: #<procedure 996c980 at ice-9/psyntax.scm:288:10 ()>>)) (#<variable 996afe8 value: #<fluid 14>> . #<variable 996aff0 value: #<procedure 996c980 at ice-9/psyntax.scm:288:10 ()>>))):
ice-9/psyntax.scm:1081:18: Syntax error:
/tmp/bug13.scm:2:0: source expression failed to match any pattern in form (define (styled-metronome-markup #:optional (glyph-font (quote default))) (lambda* (event context) "What a mess"))


-- 
David Kastrup