Re: Convert Scheme symbol to pitch

[David Kastrup]

Urs Liska <address@hidden> writes:

> Am 02.03.2017 um 22:28 schrieb address@hidden:
>> Is it possible to convert a symbol (such as `'bes'`) to a pitch (in
>> this case `(ly:make-pitch 1 0 0)`)? I know you can do `#{ bes' #}` to
>> get a pitch, but that only appears to work for constants.
>>
>> Or, for a more general question: is there some way to eval() a string
>> as Lilypond code?
>
> I'm not fully sure what you really want to achieve, but this works:
>
> {
>   #(ly:parser-include-string "bes")
> }
>
> and may help you further.

It doesn't, really.  Try

#(display (ly:parser-include-string "bes"))

ly:parser-include-string instructs the LilyPond parser (actually the
lexer) to process the string "bes" next instead of whatever it was going
to process next.  It returns no value.  And the string is only processed
once the Scheme expression finishes.  This is nice for triggering
LilyPond stuff after the Scheme expression ends.

But not much use for evaluating expressions.  See my separate proposal
instead.

-- 
David Kastrup