private static Type[] join(Type[] env1, Type[] env2) {
if (env1 == null) {
return env2;
} else if (env2 == null) {
return env1;
}
Type[] result = new Type[env1.length];
for (int i = 0; i != env1.length; ++i) {
Type t1 = env1[i];
Type t2 = env2[i];
if (t1 == null && t2 == null) {
result[i] = null;
} else if (t1 == null) {
result[i] = t2;
} else if (t2 == null) {
result[i] = t1;
} else {
result[i] = Type.Union(t1, t2);
}
}
return result;
}
