Given a year, report if it is a leap year.
The tricky thing here is that a leap year in the Gregorian calendar occurs:
on every year that is evenly divisible by 4
except every year that is evenly divisible by 100
unless the year is also evenly divisible by 400
For example, 1997 is not a leap year, but 1996 is. 1900 is not a leap year, but 2000 is.
| use base.Int.mod | |
| isLeapYear : Int -> Boolean | |
| isLeapYear year = | |
| if (mod year +4 == +0) && (mod year +100 .base.Universal.!= +0) || (mod year +400 == +0) | |
| then true else false | |
| test> isLeapYear.tests.ex1 = | |
| check ( isLeapYear +2000 == true ) | |
| test> isLeapYear.tests.ex2 = | |
| check ( isLeapYear +2015 == false ) | |
| test> isLeapYear.tests.ex3 = | |
| check ( isLeapYear +1970 == false ) | |
| test> isLeapYear.tests.ex4 = | |
| check ( isLeapYear +1996 == true ) | |
| test> isLeapYear.tests.ex5 = | |
| check ( isLeapYear +1960 == true ) | |
| test> isLeapYear.tests.ex6 = | |
| check ( isLeapYear +2100 == false ) | |
| test> isLeapYear.tests.ex7 = | |
| check ( isLeapYear +1900 == false ) | |
| test> isLeapYear.tests.ex8 = | |
| check ( isLeapYear +2400 == true ) | |
| test> isLeapYear.tests.ex9 = | |
| check ( isLeapYear +1800 == false ) |