How to automatically generate function overloads

[Blatnik]

I'm porting over my linear algebra library from C++, and I have a 
bunch of functions that work on both scalars and vectors. The 
vector versions just apply the scalar function to every element 
of the vector, for example:

```D
float clamp01(float x) { return x < 0 ? 0 : (x > 1 ? 1 : x); }

float[N] clamp01(size_t N)(float[N] vec)
{
   float[N] result;
   static foreach (i; 0 .. N)
     result[i] = clamp01(vec[i]);

   return result;
}
```

And this is great, I don't have to write the same function for 
different array lengths.

But I still have like 30-ish of these functions and I would like 
to generate the array overload automatically from the scalar 
overload.

So I would like something like a mixin, that I can use like this:

```D
mixin Vectorize_Unary_Function!clamp01; // Generates the code 
above.
mixin Vectorize_Unary_Function!floor;
mixin Vectorize_Unary_Function!ceil;
...
```

It doesn't have to be a mixin like this. I don't really care what 
it is as long as it works :)

How could I do this?