Small C++ exercise

#include <type_traits>
#include <algorithm>

//  if they are on two different types, function returs false.
template< typename T, typename U, typename F, typename G >
typename std::enable_if< !std::is_same<T,U>::value, bool >::type
check( const my_vector<T,F>& , const my_vector<U,G>& ) { return false ; }

// same type and on the same functor ...
template< typename T, typename U, typename F, typename G >
typename std::enable_if< std::is_same<T,U>::value && std::is_same<F,G>::value, bool >::type
check( const my_vector<T,F>& a, const my_vector<U,G>& b )
{
    if( a.size() == b.size() ) return std::equal( a.begin(), a.end(), b.begin() ) ;
    else return false ;
}

// on same type but different functors, create a new my_vector ...
template< typename T, typename U, typename F, typename G >
typename std::enable_if< std::is_same<T,U>::value && !std::is_same<F,G>::value, bool >::type
check( const my_vector<T,F>& a, const my_vector<U,G>& b )
{ return a.size() == b.size() ? check( a, my_vector<T,F>(b) ) : false ; }