I'm new in LISP and trying to work with deep nested lists. All the basic functions with lists such as CONS or LIST do not give correct results. They replace part of the list by symbol #.
For example:
(list '(1 (2 (3 (4 (5))))) '(6 (7 (8 (9 (10))))))
=> ((1 (2 (3 #))) (6 (7 (8 #))))
Does anyone have an idea to fix this problem?
You can adjust the depth and length of what's printed by setting the variables *print-level* and *print-length*.
(It looks like your *print-level* is 4.)
Full documentation and examples are in the HyperSpec.
One of those examples:
(setq a '(1 (2 (3 (4 (5 (6))))))) => (1 (2 (3 (4 (5 (6))))))
(dotimes (i 8)
(let ((*print-level* i))
(format t "~&~D -- ~S~%" i a)))
>> 0 -- #
>> 1 -- (1 #)
>> 2 -- (1 (2 #))
>> 3 -- (1 (2 (3 #)))
>> 4 -- (1 (2 (3 (4 #))))
>> 5 -- (1 (2 (3 (4 (5 #)))))
>> 6 -- (1 (2 (3 (4 (5 (6))))))
>> 7 -- (1 (2 (3 (4 (5 (6))))))
=> NIL
What you are seeing is the output being concatenated for brevity. The actual list is correct and not affected, but because it would be too long to print to the output, the lisp REPL shortens it when printing and uses # to indicate that it has done so.
*print-circle* to nil, but only ever do this if you're sure there are no circular structure sharing.