Eisenstein primes

class Eisenstein(a, b, w = (-1 + sqrt(3).i)/2) {
    method norm {
        a**2 - a*b + b**2
    }

    method to_s {
        sprintf('%+8.4f%+8.4fi', reals(a + b*w))
    }
}

var E = []

for e in (-10..10 ~X -10..10 -> map_2d {|x,y| Eisenstein(x,y) }) {
    var c = [e.a,e.b].map{.abs}.max
    if (
        ((0 ~~ [e.a, e.b]) || (e.a == e.b)) ?
        (c.is_congruent(2,3) && c.is_prime) : e.norm.is_prime
    ) {
        E << e
    }
}

E.sort_by { .norm }.first(100).slices(4).each {|s|
    say s.join('  ')
}

Output:

 -1.5000 -0.8660i   +0.0000 -1.7321i   -1.5000 +0.8660i   +1.5000 -0.8660i
 +0.0000 +1.7321i   +1.5000 +0.8660i   -1.0000 -1.7321i   -2.0000 +0.0000i
 +1.0000 -1.7321i   -1.0000 +1.7321i   +2.0000 +0.0000i   +1.0000 +1.7321i
 -2.0000 -1.7321i   -2.5000 -0.8660i   -0.5000 -2.5981i   -2.5000 +0.8660i
 +0.5000 -2.5981i   -2.0000 +1.7321i   +2.0000 -1.7321i   -0.5000 +2.5981i
 +2.5000 -0.8660i   +0.5000 +2.5981i   +2.5000 +0.8660i   +2.0000 +1.7321i
 -2.5000 -2.5981i   -3.5000 -0.8660i   -1.0000 -3.4641i   -3.5000 +0.8660i
 +1.0000 -3.4641i   -2.5000 +2.5981i   +2.5000 -2.5981i   -1.0000 +3.4641i
 +3.5000 -0.8660i   +1.0000 +3.4641i   +3.5000 +0.8660i   +2.5000 +2.5981i
 -3.5000 -2.5981i   -4.0000 -1.7321i   -0.5000 -4.3301i   -4.0000 +1.7321i
 +0.5000 -4.3301i   -3.5000 +2.5981i   +3.5000 -2.5981i   -0.5000 +4.3301i
 +4.0000 -1.7321i   +0.5000 +4.3301i   +4.0000 +1.7321i   +3.5000 +2.5981i
 -2.5000 -4.3301i   -5.0000 +0.0000i   +2.5000 -4.3301i   -2.5000 +4.3301i
 +5.0000 +0.0000i   +2.5000 +4.3301i   -3.5000 -4.3301i   -5.5000 -0.8660i
 -2.0000 -5.1962i   -5.5000 +0.8660i   +2.0000 -5.1962i   -3.5000 +4.3301i
 +3.5000 -4.3301i   -2.0000 +5.1962i   +5.5000 -0.8660i   +2.0000 +5.1962i
 +5.5000 +0.8660i   +3.5000 +4.3301i   -5.0000 -3.4641i   -5.5000 -2.5981i
 -0.5000 -6.0622i   -5.5000 +2.5981i   +0.5000 -6.0622i   -5.0000 +3.4641i
 +5.0000 -3.4641i   -0.5000 +6.0622i   +5.5000 -2.5981i   +0.5000 +6.0622i
 +5.5000 +2.5981i   +5.0000 +3.4641i   -4.0000 -5.1962i   -6.5000 -0.8660i
 -2.5000 -6.0622i   -6.5000 +0.8660i   +2.5000 -6.0622i   -4.0000 +5.1962i
 +4.0000 -5.1962i   -2.5000 +6.0622i   +6.5000 -0.8660i   +2.5000 +6.0622i
 +6.5000 +0.8660i   +4.0000 +5.1962i   -6.5000 -4.3301i   -7.0000 -3.4641i
 -0.5000 -7.7942i   -7.0000 +3.4641i   +0.5000 -7.7942i   -6.5000 +4.3301i
 +6.5000 -4.3301i   -0.5000 +7.7942i   +7.0000 -3.4641i   +0.5000 +7.7942i