Easter date

Easter date is difficult to calculate, but the following script made it easy:

var class="dt-set-word">easter?: func [{given a year returns the date of easter.
    lifted from "Astronomical Formulae for Caculators" pp 31 by Jean Meeus 1979
    algorithm attributed to a 1876 publication
    note: I am adding a + 1 to the day to account for an appearent rounding error
    }
    x[integer!] "(Gregorian) year"
/local a b c d e f g h i k l m n p
][a: x // 19
    b: to integer! (x /   100) c: x // 100
    d: to integer! (b /   4)   e: b // 4
    f: to integer! (b + 8 / 25)
    g: to integer! (b - f + 1 / 3)
    h: 19 * a + b - d - g + 15 // 30
    i: to integer! (c / 4)     k: c // 4
    l: 32 + e + e + i + i - h - k // 7
    m: to integer! (11 * h + a + (22 * l) / 451)
    n: to integer! (h + l - (7 * m) + 114 /   31)
    p: h + l - (7 * m) + 114 // 31
    to date! reduce[x n p + 1]
]


Usage:

>> easter? 2012
== 8-Apr-2012
>> easter? 2013
== 31-Mar-2013