[oldlaptop]

I don't (personally) like to think of the type system as "everything is an auto-mutating and cached tagged union + string" - from the perspective of someone writing in Tcl, everything absolutely is a string. It's cool that the implementation happens to store some strings as integers, or arrays, or hash tables, or whatever else as a performance hack, but unless you're actually working with Tcl_Objs at the C level, you generally don't need to care about that.

[zvr]

You are correct that, on Tcl level, everything _is_ (behaves like) a string.

But there have been too many discussions about how horrible this is for performance, that it is always worth mentioning the fact that internally this simplistic view is not true.