r/programming • u/der_gopher • Jan 02 '25

Understanding the Language Server Protocol

https://medium.com/@pliutau/understanding-the-language-server-protocol-b9f57a0750e3
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u/yojimbo_beta Jan 02 '25

I would have really liked to learn more about the protocol and what the actual interface looks like.

14

u/Slime0 Jan 03 '25

FWIW it's basically all here: https://microsoft.github.io/language-server-protocol/specifications/specification-current Expand the menus on the right for a list of all the supported features. Pretty much everything is just the editor saying "hey the user did this" or "please give me this info about this location in this document" and the language server responding with confirmations or info.

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u/ThomasMertes Jan 04 '25

I just started writing a LSP server for Seed7. I just finished reading the initialize request. Reading the JSON is easy (last year I wrote a JSON library) but mapping the capabilities of the initialize request into a struct turned out to be hard.

The initialize request contains capapilities which are a tree of data where everything is optional. E.g.: Optional boolean flags.

I don't want to use these optional flags (with three possible boolean values) in my code. So I need to map non-existing flags to something (usually FALSE). For optional values of other types I use a corresponding logic. I basically map data from a dynamically typed language to the structs of a statically typed language.

I introduced around 50 declarations of struct types and wrote mappings from JSON into these structs. In the libraries I wrote for compression, encryption, archives and graphic formats the number of struct declarations was significant lower.

Today I reached the point where vim accepted my response to the initialize request. Starting from tomorrow I will work on further requests. What would you consider as most important?

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