2.3.1 Context evaluation
Contexts can be modified during interpretation with Scheme code. The syntax for this is
\applyContext function
function should be a Scheme function that takes a single
argument: the context in which the \applyContext
command is
being called. The following code will print the current bar
number on the standard output during the compile:
\applyContext #(lambda (x) (format #t "\nWe were called in barnumber ~a.\n" (ly:context-property x 'currentBarNumber)))