BUTLAST_CONV
listLib.BUTLAST_CONV : conv
Computes by inference the result of stripping the last element of a list.
For any object language list of the form “[x0;...x(n-1)]” , the result
of evaluating
BUTLAST_CONV “BUTLAST [x0;...;x(n-1)]”
is the theorem
|- BUTLAST [x0;...;x(n-1)] = [x0;...; x(n-2)]
Failure
BUTLAST_CONV tm fails if tm is an empty list.