Email Gateway (Aug 18 2022 at 20:19): Email Gateway (Aug 18 2022 at 20:19):From: Makarius <makarius@sketis.net>
(This got stuck on isabelle-dev for quite some time, where it is basically
off-topic. See also the brief descriptions of the mailing lists on the
main Isabelle website.)
Concerning "x-symbols", there is quite a bit of confusion, including this
terminology, which stems from an obsolete Emacs package of that name from
a long time ago. Even in current Proof General 4.x there are no x-symbols
anymore, but Unicode characters for rendering the special Isabelle symbols
like \<alpha>, \<forall> etc.
In contrast to Proof General 4.x, Isabelle/jEdit (and the underlying
Isabelle/Scala) platform do the rendering of symbols in physical unicode
on the JVM by actual translation back and forth, now just by appearance.
This then allows to copy-paste in the front-end space, including other
front-end renderings like the Isabelle HTML output. It also allows the
editor to search over files using the unicode that you see on the surface,
although the prover sources are still in this encoding-free ASCII format
of Isabelle symbols. (The latter goes back to Isabelle98, and has
remained mostly stable since then, while there were several different
Unicode standards coming and going in the meantime.)
So far so good. Problems arise when you mix up front-end views (with
physical unicode rendering) and back-end sources that are given to the
prover by a side entry, without a Isabelle/Scala compliant frontend in
between. If you produce such a unicode .thy file accidentally, you can
convert it by opening in Isabelle/jEdit and saving it again with the
UTF8-Isabelle encoding that should be enabled by default. (jEdit also
allows to switch encodings explicitly, and tries to remember that choice
for later.)
Technically that encoding is managed by jEdit, independently of the raw
Java VM encoding concept for text. At some point, I might move the
UTF8-Isabelle conversion down to the JVM itself. I've also heard that the
JVM clipboard can be somehow made sensitive to encodings, with potential
alternatives. The latter might make things work yet more smoothly in the
future, but it needs further investigation of Unicode on the JVM (which is
an endless topic).
Makarius
Last updated: Nov 21 2024 at 12:39 UTC