and
Categories: Keywords procedures
, Boolean procedures
;;; (and exp1 exp2 ... expn) : any?
;;; exp1 : expression?
;;; exp2 : expression?
;;; ...
;;; expn : expression?
;;; Evaluate each expression in turn until one of them returns false
;;; or we run out expressions. In the former case, returns false
;;; (`#f`). In the latter case, returns the value of `expn`.
In the special case in which and has no parameters, returns true (#t).
and is a keyword, rather than a procedure. We see the difference primarily in that it has a different evaluation strategy than typical procedures (where we evaluate all the parameters before applying the procedure). Because and is not a procedure, we cannot use it as a parameter to higher-order procedures like map.
> (and #f #t #t)
#f
> (and #t #t #t)
#t
> (and #f 3 4 5)
#f
> (and 3 4 5)
5
> (and #f (displayln "output") 5)
#f
> (and #t (displayln "output") 5)
output
5
> (and)
#t
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