How do I define an Lilypond/Scheme alist as cons of two a lists?

Question

I have pitch names defined as a alist in Lilypond as below and it works fine. \version "2.18.2"

pitchname = #`(
                (saa . , (ly:make-pitch -1 0 NATURAL))
                (raa . , (ly:make-pitch -1 1 FLAT))


                (sa . , (ly:make-pitch -1 0 NATURAL))
                (ri . , (ly:make-pitch -1 1 FLAT))
                (ga . , (ly:make-pitch -1 2 NATURAL))                 
                )                               

#(ly:parser-set-note-names parser pitchname)

musicA = \relative sa' { sa4 ri ga sa ri ga sa ri ga ri saa ga ri sa ga raa  }

\score {\musicA}

I would like to define the variable pitchname as sum/join/append/cons of two a lists, as below:

     firstpart = #`(
                    (saa . , (ly:make-pitch -1 0 NATURAL))
                    (raa . , (ly:make-pitch -1 1 FLAT))
                   )

    secondpart = #'(
                     (sa . , (ly:make-pitch -1 0 NATURAL))
                    (ri . , (ly:make-pitch -1 1 FLAT))
                    (ga . , (ly:make-pitch -1 2 NATURAL))               
                    )

and combine the two, say:

pitchname = (cons #firstpart #secondpart)

The last statement combining the two parts is not working. Can someone tell me what I am doing wrong here?

`cons` does *not* concatenate lists. It *constructs* list. The result of `(cons head tail)` is a list whose first element is `head` then followed by the elements of `tail`. — Édouard, Sep 14 '14 at 10:34

score 1 · Answer 1 · edited Sep 14 '14 at 10:31

1

pitchname = #(append firstpart secondpart)

edited Sep 14 '14 at 10:31

Édouard

3,867
1
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answered Sep 13 '14 at 17:07

user13414

11
1

Tried that - says error: not a symbol pitchmane = (append #firstpart #secondpart) – Jay Vara Sep 13 '14 at 19:35

score 1 · Answer 2 · answered Sep 16 '14 at 09:07

There are two issues with your code.

As others noted, what you really want to do is append the alists. (Also, you forgot the leading # to escape from Lilypond to Scheme.) For comparision, this is what using cons instead would do. Note how the elements don't end up at the same nesting depth:

    pitchname = `(((saa . , (ly:make-pitch -1 0 NATURAL))
                   (raa . , (ly:make-pitch -1 1 FLAT)))
                  (sa . , (ly:make-pitch -1 0 NATURAL))
                  (ri . , (ly:make-pitch -1 1 FLAT))
                  (ga . , (ly:make-pitch -1 2 NATURAL)))

Your second list is quoted (straight apostrophe) instead of quasiquoted (backtick). You do want those make-pitch calls to be evaluated, so you can't go around the quasiquoting here.

How do I define an Lilypond/Scheme alist as cons of two a lists?

2 Answers2