Re: Scheme: Syntax for storing a variable in an alist

[Matthew Fong]

Hello Aaron and Jean,

Many thanks for pointing out the finer points of syntax of Scheme vs. LilyPond.

I appreciate the Scheme quoting reference, and the syntactic sugar. Still so much more to learn here!

Many thanks,

mattfong

On Sun, Oct 18, 2020 at 12:58 PM Aaron Hill <lilypond@hillvisions.com> wrote:

On 2020-10-18 12:42 pm, Matthew Fong wrote:
> Hello everyone,
>
> I am having a bit of an issue storing a variable in an alist, and I was
> wondering if you all could point out what I am doing wrong. If I write
> the
> string directly, there's no issue retrieving it ...
>
> my-alist = #'((1  . "A") (2 . "B") (3 . "C"))
> value = #(ly:assoc-get 2 my-alist " error")
> \markup \value
>
> hymnID = "210"
> hymnMeter = "8.8.8.8"
> hymnAlist = #'(("ID" . \hymnID ) ("Meter" . \hymnMeter ))
> hymnValue = #(ly:assoc-get "ID" hymnAlist "error")
> \markup \hymnValue

Jean already covered the bit about quasi-quoting.

But there is no need to do this as you can store values in an alist
using dot syntax in LilyPond:

%%%%
hymn.id = "643"
hymn.meter = "6 6 11 6 6 11 D"
\markup #(ly:assoc-get 'id hymn "no value")
\markup #(ly:assoc-get 'tune hymn "no value")
%%%%

\hymn automatically is an alist.


-- Aaron Hill