alt Hacker NewsThe article states, quoting:
"JavaScript's module system — introduced in 2015, thirty-two years after Ada's — provides import and export but no mechanism for a type to have a specification whose representation is hidden from importers."
Then:
"in Ada, the implementation of a private type is not merely inaccessible, it is syntactically absent from the client's view of the world."
Am I missing something -- a JavaScript module is perfectly able to declare a private element by simply not exporting it, accomplishing what the author prescribes to Ada as "is not merely inaccessible, it is syntactically absent from the client's view of the world"? Same would go for some of the other language author somewhat carelessly lumps together with JavaScript.
I loved the article, and I have always had curiosity about Ada -- beyond some of the more modern languages in fact -- but I just don't see where Ada separates interface from implementation in a manner that's distinctly better or different from e.g. JavaScript modules.
Assuming we’re talking about TypeScript here, because JavaScript doesn’t have exportable types… Any instance in JavaScript, whether or not its type is exported, is just an object like any other, that any other module is free to enumerate and mess with once it receives it. In Ada there are no operations on an instance of a private type except the ones provided by the source module.
In other words, if module X returns a value x of unexported type T to module Y, code in module Y is free to do x.foo = 42.