: gregorian-easter ( year -- month day ) [[ year.gregorian-easter ]] 2first ::: year.gregorian-easter => a := year rem: 19 b, c := year /mod: 100 d, e := b /mod: 4 f := b + 8 /i: 25 g := b - f + 1 /i: 3 h := (19 * a + b) - (d + g) + 15 rem: 30 i, k := c /mod: 4 l := 32 + 2 * e + 2 * i - (h + k) rem: 7 m := a + 11 * h + 22 * l /i: 451 n, p := h + l - 7 * m + 114 /mod: 31 n, p+1;;