Task

Determine whether a given year is a leap year in the Gregorian calendar.



See also

 Leap year (wiki)


(DEFUN LEAP-YEARP (YEAR)
    (AND (= (MOD YEAR 4) 0) (OR (/= (MOD YEAR 100) 0) (= (MOD YEAR 400) 0))))
 
; Test the function
(DISPLAY (MAPCAR LEAP-YEARP '(1600 1640 1800 1928 1979 1990 2000 2004 2005 2016)))