How to call a templated function if it exists, and something else otherwise?

I want to do something like

template <typename T>
void foo(const T& t) {
   IF bar(t) would compile
      bar(t);
   ELSE
      baz(t);
}

I thought that something using enable_if would do the job here, splitting up foo into two pieces, but I can't seem to work out the details. What's the simplest way of achieving this?