As with anything, it all goes well until it doesn't. When you have a single bug (e.g. type error or dynamic error), the guts of whatever is in the box spill out

As with anything, it all goes well until it doesn't. When you have a single bug (e.g. type error or dynamic error), the guts of whatever is in the box spill out. Case in point: all the implicit template parameters to std:: in C++ these days. The only way to add configuration options in a backwards-compatible way was to add default values for template arguments. That's all fine and good when you can't see them, but as soon as you have a nasty type error, the types that come spilling out in error messages have zillions of default arguments that get printed. It's almost always the same with inference. I would be very, very wary of doing so much type sophistry that it requires heavy inference to be usable.