Re: output some string

[Aaron Hill]

On 2018-06-15 09:40, Gianmaria Lari wrote:
> I'm trying to write some code in scheme. At the moment I do it using
> frescobaldi and I need some help for the output.
> The following code
>
> \version "2.19.81"
> #(define (f w) w)
> $(f "Hello")
>
>
> generates a pdf file containing "Hello".
>
> If my function f is called passing something that is not a string like 
> in
> the following code
>
> \version "2.19.81"
> #(define (f w) w)
> $(f '(a b c))
>
>
> it doesn't work. How can I convert my data to a string?
>
> Thank you, g.
> P.S. I have been able to write in the Lilypond log using  #(define (f 
> w)
> (write w))...

You might want to look at the `format` function:

https://www.gnu.org/software/guile/manual/html_node/Formatted-Output.html

This gives you quite a few options for formatting data and getting a 
string.

`pretty-print` can also be useful if you want to dump an arbitrary 
expression to the output.  You have to jump through a few hoops, though, 
to get its output as a string:

%%%%
  \version "2.19.81"
  #(define (pretty-print-to-string arg)
    (let ((o (open-output-string)) (s ""))
      (pretty-print arg o)
      (set! s (get-output-string o))
      (close-output-port o)
      s))
  $(pretty-print-to-string '(a b #(c d e) f . g))
%%%%


-- Aaron Hill