\version "2.17.29"

%%%%% A better slash snippet %%%

#(define (degrees->radians deg)
  (* PI (/ deg 180.0)))

% The argument `ang' is the amount of slant, expressed in degrees.
%
% Stem-fraction is the distance between the point the slash crosses the stem
% and the beam-end of the stem.  It is expressed as a number between 0 and 1.
% 
% The argument `protrusion' is the extra _vertical_ distance the slash
% extends.

slash =
#(define-music-function (parser location ang stem-fraction protrusion)
   (number? number? number?)
   (remove-grace-property 'Voice 'Stem 'direction)
   #{ 
     \once \override Stem #'stencil =
     #(lambda (grob)
       (let* ((x-parent (ly:grob-parent grob X))
               (is-rest? (ly:grob? (ly:grob-object x-parent 'rest))))
         (if is-rest?
             empty-stencil 
             (let* ((refp (ly:grob-system grob))
                     (stem-y-ext (ly:grob-extent grob grob Y)) 
                     (stem-length (- (cdr stem-y-ext) (car stem-y-ext)))
                     (line-dy (* stem-length stem-fraction))
                     (line-dy-with-protrusions (+ line-dy (* 2 protrusion)))
                     (ang (degrees->radians ang))
                     (line-dx (/ line-dy-with-protrusions (tan ang)))
                     (protrusion-dx (/ protrusion (tan ang)))
                     (dir (ly:grob-property grob 'direction))
                     (corr (if (= dir 1) (car stem-y-ext) (cdr stem-y-ext))) 
                     (stil (ly:stem::print grob)))

              (ly:stencil-add 
                stil 
                (grob-interpret-markup grob
                  (markup
                    ;#:with-color red
                    #:translate
                      (cons (- protrusion-dx)
                             (+ corr
                                (* dir
                                   (- stem-length (+ line-dy protrusion)))))
                    #:draw-line
                      (cons line-dx
                             (* dir line-dy-with-protrusions)))))))))
   #})

slashI = {
  \slash 60 0.4 0.5
}

slashII = {
  \slash 45 0.4 0.5
}

\layout {
  ragged-right = ##t
}

\new Staff { 
  \relative c'' {
    \acciaccatura {\slashI g8[ a b c] } d4 
    \acciaccatura {\slashI g8[ a b c] } d4 
    \acciaccatura {\slashI g8[ a b c] } d4 
    \acciaccatura {\slashI g8[ a b c ] } d4 
  } 
  \relative c' { 
    \clef bass 
    %\break
    \acciaccatura {\slashII d8[ c b a ] } g4 
    \acciaccatura {\slashII d8[ c b a ] } g4 
    \acciaccatura {\slashII d8[ c b a ] } g4 
    \acciaccatura {\slashII d8[ c b a ] } g4 
  } 
}

\new Staff { 
  \relative c'' {
    \acciaccatura {
      \slash 45 0.4 0.5
      dis32[ e, a' bes, cis, d' ]
    }
    es,4
    \acciaccatura {
      \slash 60 0.4 0.7
      dis'32[ e, a' bes, cis, d' ]
    }
    es,4
  }
}