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[Giovanni Piredda <address@hidden>]

On 08.01.22 20:19, vincent douce wrote:
> hi
> before i post this on 
> https://savannah.gnu.org/task/?group=texmacs&func=additem 
> <https://savannah.gnu.org/task/?group=texmacs&func=additem>
>
> could you tell me if maybe it still exists :
> - transform a/b into b/a (with the same type of fraction, "frac", 
> "dfrac" etc)

I have copied the example in the Scheme developer guide


(define (swap-numerator-denominator t)
(:require (tree-is? t 'frac))
(with p (tree-cursor-path t)
(tree-set! t `(frac ,(tree-ref t 1) ,(tree-ref t 0)))
(tree-go-to t (cons (- 1 (car p)) (cdr p)))
(tree-focus t)))

(define (swap-numerator-denominator t)
(and-with p (tree-outer t)
(swap-numerator-denominator p)))

end of Sect. 3.2, "A worked example", but I did not yet get it to work. 
I'll update you when I make a step forward