(dec' x)
Returns a number one less than num. Supports arbitrary precision. See also: dec
user=> (dec' 0.1)
-0.9
user=> (dec' 1)
0
user=> (dec' 1.0)
0.0
;;;; (dec') auto-promotes on integer overflow:
(dec' (Long/MIN_VALUE))
;;=> -9223372036854775809N
;;;; Unlike (dec) which does not:
(dec (Long/MIN_VALUE))
;;=> ArithmeticException integer overflow