CAS-> Variable() warning msg?

[Han]

Try this:

restart;
a:=x^2;
x:={1,2,3,4};
a(1);
a(2);
a(3);
a(4);
a(-1);
a(5);

The last two produce an error. On the other hand, using:

restart:
a(x):=x^2;
x:={1,2,3,4};
a(1);
a(2);
a(3);
a(4);
a(-1);
a(5);

will result in no failures.