Interfacing with user-supplied binary or obj file

[TheZipCreator]

So I'm making an interpreter for my custom scripting language and 
I want to allow users to write libraries in languages other than 
said scripting language (for efficiency). For example, you should 
be able to write a mathematics library in D, compile it, then 
write a simple wrapper in my language and then be able to import 
it to your script to use (similar to a lot of Python libraries). 
So how exactly could I do this without requiring to user to 
recompile the interpreter every time they want to use a new 
library? Is there some way I could dynamically link in compiled 
.obj files?