Re: [Scheme coding] turning a list into a markup/string

[David Nalesnik]

Hi Kieren!

On Tue, Jan 21, 2020 at 1:52 PM Kieren MacMillan
<address@hidden> wrote:
>
> Hi all,
>
> Here’s a perfect example of why I keep stumbling (and stopping) when trying 
> to learn Scheme+Lilypond…  =\
>
> With Mike S’s help — read: he did it all, actually! (though I fully 
> understand every part of the code) — I have the following:
>
> %%%  SNIPPET BEGINS
> \version "2.19.83"
>
> some-music = { a'4 bes' b' aes' g' cis' d' ees' fis' f' e' c' }
>
> #(define (zip . xss) (apply map list xss))
>
> #(display
>  (let* ((res (map
>               (lambda (foo) (ly:pitch-semitones (ly:music-property foo 
> 'pitch)))
>               (ly:music-property  some-music 'elements)))
>         (top (reverse (cdr (reverse res))))
>         (bottom (cdr res)))
>    (map (lambda (h) (- (cadr h) (car h))) (zip top bottom)))
>  )
> %%%  SNIPPET ENDS
>
> Works great. Just what I want at this stage in the (multi-stage) procedure 
> I’m trying to code.
>
> As the next step, I want to turn this into a function and display the result 
> in a markup. Result: I spend several hours searching documentation, trying 
> different functions, and getting one (or more!) errors per attempt, but no 
> success. I literally cannot figure out how to turn this into a string, save 
> hand-coding a recursion/map that takes each element of the list and appends 
> it onto a string… and if that’s actually the "correct"/"best" way to do it, 
> then I deeply question my desire to code in Scheme+Lilypond at all.  ;)
>
> So someone please tell me what simple thing I’m missing here. In the worst 
> case scenario, you just give me a fish and I can eat for a little while 
> longer (read: not give up); best case senario, you teach me (and anyone else 
> reading this list, now or in the future in the future) how to fish.
>
> Thanks,
> Kieren.

Try this:

%%  SNIPPET BEGINS
\version "2.19"

some-music = { a'4 bes' b' aes' g' cis' d' ees' fis' f' e' c' }

#(define (zip . xss) (apply map list xss))

#(define-markup-command (pitch-info layout props args) (ly:music?)
   (let* ((res (map
                (lambda (foo) (ly:pitch-semitones (ly:music-property
foo 'pitch)))
                (ly:music-property some-music 'elements)))
          (top (reverse (cdr (reverse res))))
          (bottom (cdr res))
          (ls (map
               (lambda (h) (- (cadr h) (car h)))
               (zip top bottom)))
          (markups (map
                    (lambda (elt) (make-simple-markup (number->string elt)))
                    ls)))
     (interpret-markup layout props #{ \markup \line #markups #})))

\markup \pitch-info #some-music
%%%  SNIPPET ENDS

Hope this gets you started with whatever dodecaphonic plans you have...

David