Hello Jacques,
> There have been very interesting discussions about all this at the
> Salzburg conference last January, which lead me to dream of things
> being done another way in an ideal world: [...]
>
> - switch to another, easier to read and write extension language.
> Someone suggested Lua, for example, which would be a good
> candidate it seems;
This could only happen as an addition. Compare this to `pandoc`: For
many people the native Haskell is too exotic to write extensions, thus
Lua was added as a simpler solution.
> [...]
>
> - rely only on C++, flex, bison and the extension language.
> Eliminating the need for GUB and Python would greatly simplify
> porting LilyPond to various environments, including web sites,
> phones and tablets.
GUB will be history soon, thanks to the work mainly of Jonas. It's
not clear to me why you want to eliminate the use of Python.
Werner