Gianmaria Lari <gianmarial...@gmail.com> writes: > Probably these are very trivial things. Sorry to ask them but would like to > understand. > > If I write (1): > > > \version "2.19.82" > $(object->string (+ 3 2)) > > > Lilypond is happy and compile to a pdf file showing "5". > > Even this simpler code works... (2) > > \version "2.19.82" > $"Hello" > > > and generate a pdf file showing "Hello". > > It is clear to me that $ introduce a scheme expression that is evaluated. > And in the previous two examples the scheme code is evaluated to strings. > But I don't understand why lilypond outputs them. If I write (3): > > \version "2.19.82" > "Test"
blabla = "Test" ##f \blabla will compile again (sorry for the ##f : it is necessary to defeat lookahead). It is indistinguishable from blabla = \markup "Test" ##f \blabla in output and in its effect on the variable. Basically, $x and \x are the same (apart from the characters allowed in and after x). The logical thing would be to permit "Test" on its own but it appears rather error-prone. This is similar to blabla = c4 ##f \blabla compiling and producing a result while c4 on its own doesn't. > I tried to rewrite (1) and (2) with the hash mark instead of dollar (6): > > \version "2.19.82" > #(object->string (+ 3 2)) > > > and (7): > > \version "2.19.82" > #"Hello" > > > This time, there is no output in the pdf file. Why this difference? At the top level of the file, assignments and assignment-like statements may be executed. The return value of an assignment in Scheme is unspecified. There are things like #(set! (hashq-ref x y) z) that somewhat inscrutably return an actual value other than *unspecified*. For that reason, # expressions in contexts where assignments are allowed are evaluated and ignored. Use $ if you want them to be heeded. -- David Kastrup _______________________________________________ lilypond-user mailing list lilypond-user@gnu.org https://lists.gnu.org/mailman/listinfo/lilypond-user
