Comment by jesse__
13 hours ago
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..
It's not network requests that are a problem. It's nondeterministic network requests. Build systems do make network requests, but assuming the network is up and the build servers are running, the result of a compile should always be the same. If the server isn't reachable then the build fails.
Also, while build systems can do stuff over the network, the program isn't allowed to run arbitrary network code at compile time. At most it can import a library at a particular URL. The build system will need to download the library the first time, but it can also cache libraries so no download is needed.
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A compiler is allowed to halt on a syntax error. Syntax highlighters ideally should not give up on colouring the rest of the document due to mismatched parentheses (or braces or any other delimiter pair).
Many syntax highlighters in fact do so, but this simply isn't what the point was about network indeterminacy--compilation determines the semantics of the program being compiled, syntax highlighters do not.
Fair point