"const" means something can't be changed. "mutable" means it can be changed.
You don't need both a "const" keyword and a "mutable" keyword in a programming language. You only need 1 of the keywords, because the other can be the default. munchler is saying the "const" keyword shouldn't exist, and instead all variables should be constant by default, and we should have a "mutable" keyword to mark variables as mutable.
As opposed to how C++ works today, where there is no "mutable" keyword, variables are mutable by default, and we use a "const" keyword to mark them constant.
"const" means something can't be changed. "mutable" means it can be changed.
You don't need both a "const" keyword and a "mutable" keyword in a programming language. You only need 1 of the keywords, because the other can be the default. munchler is saying the "const" keyword shouldn't exist, and instead all variables should be constant by default, and we should have a "mutable" keyword to mark variables as mutable.
As opposed to how C++ works today, where there is no "mutable" keyword, variables are mutable by default, and we use a "const" keyword to mark them constant.
> you don't need both a "const" keyword and a "mutable" keyword
What if the lang has pointers? How express read-only?
You can make everything read-only by default, and if you need non-read-only, you use "mutable".
You need two keywords. One for assignability and one for writability :
compiler flags with line and column number seems like the easiest way