Implementing dynamic typing in C

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Representing dynamic typing in C

A professor at my History of Computation side-lecture went into great depth about manifestly typed or type-inferred languages and generally praised the greatness of latently typed languages (faster dev times, dynamic systems, etc...).

The same day, at an Automata Class, another prof says:

Dynamic typing makes things more complex by adding more ways to do the same thing.

I've been using statically typed languages most of my life : C/C++/Java - my only exposure to the other has been Shell Coding and Ren'Py.

My question is, can I write a simple program in C that implements some of the benefits of both ?

For instance, I could create Unions to accept all user driven data, like so :

    typedef union {
        int int_type;
        char char_type;
        //and so on
    } dynamic;

   // Var Creation :
   dynamic data;

   // For unknown return type
   void* function(dynamic data);

I realize a Union could compromise type-safety, but that is what I'm trying to do here. What other approach could I take ? I'm just trying for a demonstration.

I tried for an answer from this question. But honestly, I could not follow the arguments closely.

I apologize if the question seems silly.

PS

Using suggestions from below, I wrote this : http://codepad.org/A9JAX8lD, which basically does nothing much dynamic, but is at least a start.
I think I see what both my professors were trying to say.