REBOL [
    Title: "Leap-Year"
    Date: 3-Jul-2002
    Name: Leap-Year
    Version: 1.0.0
    File: %Leap-Year.r
    Author: "Andrew Martin"
    Purpose: "Returns true for a leap year."
    Email: Al.Bri@xtra.co.nz
    Web: http://valley.150m.com
    Category: [util math 1]
]

Leap-Year?: function [
    "Returns true for a leap year."
    Date [date!]    "The date to check."
    ] [Year] [
    Year: Date/year
    any [
        all [
            0 = remainder Year 4
            0 <> remainder Year 100
            ]
        0 = remainder Year 400
        ]
    ]