[procedure] member obj list

R5RS: Returns the first sublist of list whose car is equal? to obj. If obj does not occur in list, then #f (not the empty list) is returned.

See also memq, memv.

[procedure] member obj list [=]

SRFI-1: This is an upper-compatible extension of R5RS member, to allow the client to pass in an optional equality procedure = used to compare keys.