Improving the development experience with language servers

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Vinicius Stock Improving the development experience with language servers

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Vinicius Stock Senior dev @ Ruby DX team Shopify Twitter: @vinistock GitHub: @vinistock https://vinistock.com

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Let’s look back

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Vim Ruby Source: https://code.visualstudio.com/api/language-extensions/language-server-extension-guide Editors Plugins JavaScript Rust Go Sublime VS Code Neovim

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No standard set of language speci fi c features

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Vim Ruby Source: https://code.visualstudio.com/api/language-extensions/language-server-extension-guide Editors Plugins JavaScript Rust Go Sublime VS Code Neovim Syntax highlighting Go to de fi nition Linting

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Language Server Protocol Set of standard features Source: https://microsoft.github.io/language-server-protocol/speci fi cation Background server

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Language server STDIN Editor (Client) Request (JSON) Response (JSON) STDOUT STDERR

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Vim Ruby Source: https://code.visualstudio.com/api/language-extensions/language-server-extension-guide Editors Language server JavaScript Rust Go Sublime VS Code Neovim Client Client Client Client Plugin or built-in

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Source: https://microsoft.github.io/language-server-protocol/speci fi cation

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Source: https://microsoft.github.io/language-server-protocol/speci fi cation

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initialize textDocument/ didOpen textDocument/ foldingRange Language server Editor (Client) capabilities Activate language server Open fi le foo.rb Ranges Edit foo.rb textDocument/ didChange Ranges textDocument/ foldingRange

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Ruby LSP https://github.com/Shopify/vscode-ruby-lsp https://github.com/Shopify/ruby-lsp

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What does it do?

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Let’s see how to server works

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Loop STDIN Read JSON request Run request STDOUT Write JSON response

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Ruby LSP Text synchronization Parsing Hover Document highlight Folding range Document symbol

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How can we implement it?

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Source: https://microsoft.github.io/language-server-protocol/speci fi cation

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Source: https://microsoft.github.io/language-server-protocol/speci fi cation

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AST Ruby code Analysis Parse Traverse

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What’s parsing?

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AST simpli fi ed from the syntax_tree gem CLASS BODY CONST DEF IDENT BODY STRING

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We need a way of going through each node

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BODY CONST DEF IDENT BODY STRING CLASS

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We’re ready to implement folding range

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Synchronize text edits Parse Folding range Document symbol Document link Semantic highlighting Inlay hint Selection range AST

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Ruby LSP https://github.com/Shopify/vscode-ruby-lsp https://github.com/Shopify/ruby-lsp

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Folding range Document symbol Document link Semantic highlighting Inlay hint Selection range Hover Format on type Document highlight Format on save Diagnostics Code actions

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The future of Ruby tooling

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Rich features Cross editor Gradual typing Interactive debugging Any editor can be a fully featured IDE

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Thank you!

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• https://github.com/Shopify/vscode-ruby-lsp • https://github.com/Shopify/ruby-lsp • https://code.visualstudio.com • https://github.com/ruby-syntax-tree/syntax_tree • https://microsoft.github.io/language-server-protocol/speci fi cation • All screenshots made with: https://code.visualstudio.com References