why can't use do something like this?
```d
import std.stdio : writeln, writefln;
void main()
{
writeln("Hello");
}
```
and pass a file like:
rdmd aa.d --eval="write(\"hello\");"
returns
```
object.Exception@rdmd.d(193): Cannot have both --eval and a
program file ('eval.d').
----------------
??:? pure @safe void
std.exception.bailOut!(Exception).bailOut(immutable(char)[],
ulong, scope const(char)[]) [0x50e882]
??:? pure @safe bool
std.exception.enforce!().enforce!(bool).enforce(bool, lazy
const(char)[], immutable(char)[], ulong) [0x57954f]
??:? _Dmain [0x505753]
```
