Comment by jesse__ 17 hours ago
Off the topic of dependent types, but this is way too hilarious to pass up..
> Imagine if pickType did a network request to a server and then returned whatever type the server said. Sounds like a bad idea!
Fucking .. isn't this what LSPs are?! Finally something functional programming people and I can agree on. That does sound like a bad idea.
What's the fundamental difference between a syntax highlighter and the frontend of a compiler? I would argue not much, apart from the fact that people are willing to have their syntax highlighter randomly explode, but are much more concerned about their compiler randomly exploding.
The fundamental difference is that a compiler's actions determine the semantics of the program; a syntax highlighter has no effect on it. And I don't think the concern here is about things blowing up. (Not that things blowing up isn't concerning, but it just doesn't have anything to do with this discussion.)
The fundamental difference is that in his case any conforming compiler has to do the network request. Whereas with LSP it's just an implementation detail of the editor.
The fundamental difference is that a compiler determines the semantics of the program being compiled, and having that be non-deterministic is disastrous ... whereas a syntax highlighter has no effect on the semantics of the program that is generated from the code being highlighted. Things blowing up is a complete red herring.
My point is "why do we tolerate network requests in LSPs, but not compiler frontends"?
If you think about it, the LSP is a way of doing libraries, which is dramatically worse than just inventing a binary interface and doing actual dynamic libraries.
If you follow the LSP model to it's natural conclusion, everything becomes this horrible, disconnected morass of servers talking to each other on your local machine..
So, you're saying it's outside the scope of an LSP to return information about a dependent type because it's .. not a concrete type? That sounds wrong.
I can make literally any language support dependent types that have struct, enum, switch, and assert. You make a boxed type (tagged union, algebraic datatype, variant, discriminated union, fucking, whatever), and just assert whenever you pack/unpack it on function entry/exit. I do this all the time.
In plain English, my quip boils down to 'why do we tolerate network requests in our syntax highlighters, when we don't tolerate them in our compiler frontends?'
This is easily the stupidest thing I've read on HN in quite a while, and your continued arrogance in the rest of the thread doesn't help. Quite an achievement for a site so full of people who have a direct line from their ass to the comment section. Congratulations!
I think it's a bit apples and oranges. I was suggesting that compilation itself should probably not involve nondeterministic network requests. If I understand LSP correctly, it only uses network requests to allow your editor to communicate with a binary that provides type information. But the compiler behavior is unchanged. Honestly LSPs seem pretty reasonable to me.