The subseq_abbreviation mechanism was a useful way of quoting some of a
definition or term, specialised to the case of left-associated sequences.
Lambda abstractions are now handled better.
The previous subseq mechanism required some generalisations. It is now replaced
by match_abbreviation, which is a more general approach.
The match mechanism picks a term, can select a matching subterm, and can
rewrite the selected term based on pattern matching also. The new mechanism
can cover all the cases of the previous one, as shown in examples.
Japheth Lim
Thomas Sewell