----------------------------------------------------------------------
BUTLASTN_CONV                                                (listLib)
----------------------------------------------------------------------
BUTLASTN_CONV : conv

SYNOPSIS
Computes by inference the result of dropping the last n elements of a list.

KEYWORDS
conversion, list.

DESCRIBE
For any object language list of the form {“[x0;...x(n-k);...;x(n-1)]”} ,
the result of evaluating

   BUTLASTN_CONV “BUTLASTN k [x0;...x(n-k);...;x(n-1)]”

is the theorem

   |- BUTLASTN k [x0;...;x(n-k);...;x(n-1)] = [x0;...;x(n-k-1)]




FAILURE
{BUTLASTN_CONV tm} fails if {tm} is not of the form described above,
or {k} is greater than the length of the list.

----------------------------------------------------------------------