In Common Lisp how do I search for a sublist within a list

Question

If I want to find whether (x 2) exists within a list containing ((x 2) (y 2) (z 2)) for example, how do I do this?

(member '(x 2) '((x 2) (y 2) (z 2)))

returns NIL as does find

Thanks for the help

possible duplicate of [Test if array is inside a list in lisp](http://stackoverflow.com/questions/19287777/test-if-array-is-inside-a-list-in-lisp) — sds, Jan 02 '14 at 15:35
possible duplicate of [how to test whether one list is a member of another](http://stackoverflow.com/questions/19612193/how-to-test-whether-one-list-is-a-member-of-another) — Joshua Taylor, Jan 03 '14 at 18:27

score 5 · Accepted Answer · edited May 23 '17 at 11:44

5

? (member '(x 2) '((x 2) (y 2) (z 2)) :test 'equal)
((X 2) (Y 2) (Z 2))

In Common Lisp, member uses eql as the default test, which does not work in this case.

See here for details regarding eq, eql, equal and equalp.

edited May 23 '17 at 11:44

Community

answered Jan 02 '14 at 14:23

uselpa

@mbratch `eql`, actually. What is `equ`? – uselpa Jan 02 '14 at 14:52
Hehe oops, I meant `eql`. My bad. I'm bouncing betwixt too many different languages... ;) – lurker Jan 02 '14 at 16:05

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