I am trying to generate an array of prime numbers using constraint. But the code is printing an empty array. Where am I wrong?

class abc;

rand bit [4:0] a;

int i;

constraint a0{a.size() == 100;}

constraint a1{ foreach (a[i])

a[i] == prime(a[i]);}

function integer prime (int val);

if (val <=1) return 0;

for(i=2;i<val/2;i++)begin

if(val%i==0)

break;end

return val;

endfunction

endclass

module xyz;

initial begin

abc m_h;

m_h = new();

m_h.randomize();

$display(“\n Array of Prime with %0p”, m_h.a);

end

endmodule

Output is :

A is '{}