As someone who is extremely unfamiliar with category theory, types, and C++, something is bothering me that I would love to have clarified.
Polymorphic function templates are introduced with addEm:
template
T addEm(T a, U b)
{
return a + b;
}
template
inline T max(T a, T b) {
return a > b ? a : b;
}
The implication in the first example seems to be that if you want your template to be compatible with more than one type, you must explicitly indicate so in your template parameters. However, the Wikipedia entry seems to indicate that C++ implicitly instantiates object code for as many types as the template is called on at compile time, a function instantiated for each of the types (addEm, addEm, addEm, etc.), and a compilation error resulting if inputs of different types are passed to the template.
Am I missing something? For reference, here is how I would intuit the first example should look, based on my current understanding.
template
T addEm(T a, T b)
{
return a + b;
}