[isabelle-dev] [isabelle] Tiny minor backward-compatible changes to IFOL

[Makarius]

On 02/05/2020 16:43, Manuel Eberl wrote:
> Seems reasonable to me.
> 
> As I said already privately, there should then definitely be an
> abbreviation for entering ∃⇩≤⇩1 using autocomplete.

This works via 'abbrevs' in the theory header; e.g. see theory
HOL-Library.FuncSet:

theory FuncSet
  imports Main
  abbrevs PiE = "Pi\<^sub>E"
    and PIE = "\<Pi>\<^sub>E"


An alternative is to use "!" as originally proposed by Georgy Dunaev. My
impression is that only the oldest users of Isabelle/FOL or HOL remember the
historic use of "!" for universal quantification.

With a tiny little bit of effort we could have a version of "isabelle update"
that replaces all remaining uses of "!" automatically.

That would be a contribution to ecology and health of features.


	Makarius