Earlier quoted context omitted.
One small detail - though COND and IF/ELSE are very closely related, they aren't quite the same thing. Early Smalltalk also started out with COND (a right arrow which made code look like modern switch/case) and later evolved to #ifTrue:ifFalse: which is still postfix, so feels backwards compared to other languages. Lisp and Scheme got more conventional if/else eventually.
Something I discovered about Clojure's cond recently. It usually looks likethis: (cond ( a b) (println "a > b") :else (println "a = b")) I thought the :else had to be :else, but it only needs to be truthy, so it can be anything that isn't false or nil (which makes sense as you want it to always execute that form if no others match). So this is just the same: (cond ( a b) (println "a > b") :hotdog (println "a = b")) P…
There is an interesting situation is in the case family of constructs which match an input value against keys, in Common Lisp.
Inspired by cond, the t symbol also serves as the fallback in case when the key doesn't match the other cases. So that is to say:
(case (expr)
(a ...)
(b ...)
(42 ...)
(t ...)) ;; But the programmer may also sometimes have the t symbol as a specific key value; or likewise the otherwise symbol. That requirement is handled by putting the key into a list:
(case (expr)
(a ...)
...
((t) ...)) ;;