Bidirectional constraint solving. It's bad for compile time but even worse for predictable diagnostics. Mojo does contextual resolution, but it works more similar to how C++ resolves initializer lists etc.
> Bidirectional constraint solving. It's bad for compile time but even worse for predictable diagnostics.
That’s really only true if you have overloading though! Without overloading there are no disjunction choices to attempt, and if you also have principal typing it makes the problem of figuring out diagnostics easier, because each expression has a unique most general type in isolation (so your old CSDiag design would actually work in such a language ;-) )
But perhaps a language where you have to rely on generics for everything instead of just overloading a function to take either an Int or a String is a bridge too far for mainstream programmers.
Mojo has overloading, generics and a much more advanced type system than Swift (dependent and linear types etc), and compile time in all phases is very important. The Mojo design seems to be working well - it gives expressive power, good error messages etc.
slavapestov|5 months ago
That’s really only true if you have overloading though! Without overloading there are no disjunction choices to attempt, and if you also have principal typing it makes the problem of figuring out diagnostics easier, because each expression has a unique most general type in isolation (so your old CSDiag design would actually work in such a language ;-) )
But perhaps a language where you have to rely on generics for everything instead of just overloading a function to take either an Int or a String is a bridge too far for mainstream programmers.
chrislattner|5 months ago
It feels like a much better design point overall.