While Lisp is usually associated with FP practices, the CLOS (Common Lisp Object System) really helped me with getting OOP to click as a concept. Part of it is

While Lisp is usually associated with FP practices, the CLOS (Common Lisp Object System) really helped me with getting OOP to click as a concept. Part of it is that, CLOS is just Lisp, so all of the concepts of OO programming are there with none of the syntax generally added in other OO languages. Also, the method/function names clearly name all the concepts instead of using opaque notation: SLOT-VALUE instead of dot, arrow, or double-colon notation, DEFCLASS does what it says on the tin instead of the vaguer "class ClassName { }" of C++/Java/etc. I feel like this makes it clearer what is happening. A good overview of CLOS is chapters 16 and 17 of /Practical Common Lisp/ (http://www.gigamonkeys.com/book/ http://www.gigamonkeys.com/book/) I've heard other people speak similarly of learning Perl's MOOSE after already being familiar with non-OO Perl. This probably is no coincidence since MOOSE is heavily inspired by CLOS.