Arrows

The standard way to create an arrow is to combine a line with an arrow-head glyph.

However the line and the glyph will not follow the same scale when the global-staff-size changes.

Here's a markup function that helps to create ready to use arrows that avoid this problem.

Syntax is \arrow #'type #'fletching #'axis #'direction #'length #'boldness.

Example (at default global-staff-size):

\markup{ \scale #'(1.8 . 1.8) \arrow #"open" ##f #Y #UP #3 #0.14 }
will give the same output as:
\markup{ \combine \fontsize #5 \arrow-head #Y #UP ##f \override #'(thickness . 2.4) \draw-line #'(0 . -5.4) }

See bellow's the arrows list with optimal boldness (the one each arrow type was designed for).