Type inference for constructor parameters with default values

[tieskedh]

Why can not type of function parameters with default value be omited?

The main reason is compilation performance. When we look at a method call, it helps a lot to have explicit parameter types which don’t need to be inferred. Inferring the parameter type from a string constant is trivial, but if you have fun foo(a = bar()) and bar() also has an inferred return type, understanding the actual parameter type of a becomes very expensive.

But there is an issue on Youtrack for what you want:

https://youtrack.jetbrains.com/issue/KT-19046