You can call any constraint imposed by the language a type and that may be true in the abstract sense, but what counts when talking about types in a language is

You can call any constraint imposed by the language a type and that may be true in the abstract sense, but what counts when talking about types in a language is what the language's own type system has to say on the matter What counts isn't so much what the specification calls a 'type' but rather how the compiler does type reduction - and with all of the compilers I've worked with, argument decorators like 'in' & 'out' are typically handled during type reduction. depending on how the compiler chooses to pass the values. Note that even 'in out' parameters may be passed by value through a 'pass by copy-in copy-out' mechanism, so whether a parameter is passed by value or reference is largely handled behind the scenes, so the type system doesn't include that information. If it did, Ada would be even more verbose and unwieldy than its reputation suggests, as type enforcement is much more strict in Ada. Very interesting! I know very little about Ada - other than that it has generally been considered as a safer alternative to C for applications-programming in the aerospace software world. At the same time, I can say that without the ability to determine the how of how the compiler will pass arguments - by value, by copy, by reverse copy, by reference - I wouldn't consider Ada to be an alternative to C in the systems-programming domain, any more than I would consider Haskell or Javascript to be systems-programming languages. Your original claim, in your words, was that 'const' in C and C++ is broken. C, or any other systems-programming language, simply has more constraints on what const could possibly be. The Ada approach to handling const would simply never work in C with C's implementation guarantees. To pseudo-quote a great man, Dennis Ritchie, If you want magical argument passing, sometimes resulting in silent and unexpected argument copying, you know where to get it.