Major Section: PROGRAMMING
For any natural numbers start
and end
, where start
<=
end
<=
(length seq)
, (subseq seq start end)
is the
subsequence of seq
from index start
up to, but not including,
index end
. End
may be nil
, which which case it is treated
as though it is (length seq)
, i.e., we obtain the subsequence of
seq
from index start
all the way to the end.
The guard for (subseq seq start end)
is that seq
is a
true list or a string, start
and end
are integers (except,
end
may be nil
, in which case it is treated as (length seq)
for ther rest of this discussion), and 0
<=
start
<=
end
<=
(length seq)
.
Subseq
is a Common Lisp function. See any Common Lisp
documentation for more information. Note: In Common Lisp the third
argument of subseq
is optional, but in ACL2 it is required,
though it may be nil
as explained above.