Fermata with parenthesis

[wjm]

You wrote:-
+++++++++++++++++++
I would like to ask for some advice on writing functions using Scheme.
I'm looking to have a up fermata object with parenthesis,
+++++++++++++++++++++++++++++++

At the risk of seeming naive, I ask whether you are reinventing the 
wheel with this particular example?

A search on the 'net finally found an earlier question with the 
following answer:-
>>"... The parentheses are a bit too small in comparison to the fermata

>You can apply an override for this.   See
>http://lsr.dsi.unimi.it/LSR/Item?id=421 "

which leads to this
{ c b e
\once \override ParenthesesItem #'font-size = #-1 %this line precedes 
the note with the fermata
c-\parenthesize\fermata  }

Hope this helps - although it doesn't do anything for your request for 
help with Scheme! :)

Regards
Bill