On Fri, Feb 21, 2020 at 3:49 AM Matt Hurd via Std-Proposals <std-proposals@lists.isocpp.org> wrote:

For aggregates you don’t need to write constructors. For double/other non-integrals it would be as simple as
struct radians{
   double value;

Also, I suppose a question would be how you intended to get the value out of the “new” types. If by static_cast, I could see the removal of the boilerplate to get that being a potential positive for your method (though maybe not enough to justify a core language extension, I don’t know). 
I currently get by with a suite of macros and hana introspection to add relational, iostream, and arithmetic operations as is appropriate to value wrappers and aggregates. I wrote the OP shortly after yet another frustrating debugging session with hana's EqualityComparable on Struct concepts. Simple things should be simple is my thought for the day :-)

This is not simple however. Strong typedef are researched (multiple papers by "best minds") for 20 years and they appear simple only on the surface.  Once you dig enough on exactly what the semantics are going to be you end up with an entire new sub-system with its sub-langauge
And this is in direct competition to the already available wrapping, making hard sell.
In the meanwhile there are many small improvements that diminish their values further by making current and alternative ways easier - enum class for ints, inherent ctors, spaceship op, soon reflection, "soon" language variant 

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