symbol rebinding

[MartinNowak]

It should be possible to rebind previous declared symbols to something else.

string foo = "bar";

int foo = 3;

This requires to keep track of declared symbols and excluding rebinded symbols from the imports.

module _mod1;

string foo = "bar";

module _mod2;
import _mod1 : foo;

int foo = 3;

module _mod3;
import _mod2 : foo; // doesn't import _mod1 : foo

//

Using selective imports allows to correctly implement function overload.
In that case both selective imports are present.

[MartinNowak]

Keeping track of symbols would allow to reference count the shared libraries and free them if all symbols are reused.

[lindt]

this bug prevents drepl from being usefull in jupyterd.