Editor Integration (LSP)

Resilient ships an opt-in Language Server that wires up red-squiggle diagnostics, hover, go-to-definition, and completion in any editor that speaks LSP.

Table of contents

Build

The LSP server pulls in tower-lsp + tokio, so it’s gated behind a feature flag. Default builds don’t pay the cost.

cargo install --path resilient --features lsp
# `rz` lands in ~/.cargo/bin/rz with LSP support compiled in.

Running rz --lsp against a build without the feature emits a helpful error and exits non-zero.

Start the server 

rz --lsp

The server communicates over stdin/stdout using the standard JSON-RPC LSP framing. Your editor client manages the process.

What’s implemented

Diagnostics

Every did_open or did_change event re-runs the full parse + typecheck pipeline and publishes structured diagnostics with <uri>:<line>:<col>: locations. Editor squiggles appear in the reported column for parser and typechecker errors; lint diagnostics use the source positions recorded by the lint pass.

Hover

Hovering over any literal token shows its surface type:

Literal Hover shows
42 Int
3.14 Float
"hi" String
true Bool

Hovering over identifiers also returns current best-effort type or signature information for top-level let, const, static let, top-level function names, function parameters, and local let bindings. Names outside those supported scopes return no hover instead of a guessed type.

Go-to-definition

Clicking “go to definition” on any top-level function or struct name jumps to its declaration site in the current file or an imported workspace file. Workspace lookup follows use "..." imports for top-level functions and structs, including unopened files under the initialized workspace folder.

Find references

Running “find references” on a supported identifier returns LSP locations for:

  1. Top-level functions across the current file and imported workspace files.
  2. Struct types across the current file and imported workspace files.
  3. Same-file variable declarations, reads, and writes.

The client controls whether the declaration site is included through the standard includeDeclaration request flag.

Rename

Rename requests use textDocument/prepareRename first, so editors can reject unsupported cursor positions before prompting for a new name. Supported targets are top-level functions, top-level structs, and top-level let, const, or static let bindings.

textDocument/rename validates the new identifier, rejects names that would shadow an existing visible top-level binding, and returns a workspace edit for matching references in open documents and workspace .rz files.

Symbols

textDocument/documentSymbol returns a source-ordered outline for top-level functions, structs, and type aliases in the current file.

workspace/symbol indexes .rz files under the initialized workspace folder and returns matching top-level symbols across those files.

Code actions

textDocument/codeAction offers quick fixes derived from diagnostics. Current actions include adding requires true; / ensures true; contract stubs for no-contract lint diagnostics, inserting a missing semicolon, suppressing lint diagnostics with // resilient: allow, prefixing unused variables or dead functions with _, adding numeric as <type> casts for type mismatches, and adding use "..." imports for undefined names found in the workspace index.

Completion

Triggering completion offers:

  1. All built-in functions, alphabetical (abs, ceil, floor, …).
  2. Every top-level declaration in the current file (functions, structs, type aliases), alphabetical after builtins.

Scope-aware local-variable completion and post-dot field completion are follow-up tickets.

Editor setup

Neovim (nvim-lspconfig) 

local lspconfig = require("lspconfig")
local configs   = require("lspconfig.configs")

if not configs.resilient then
  configs.resilient = {
    default_config = {
      cmd      = { "/absolute/path/to/rz", "--lsp" },
      filetypes = { "resilient" }, -- .rz files
      root_dir  = lspconfig.util.root_pattern("Cargo.toml", ".git"),
      settings  = {},
    },
  }
end
lspconfig.resilient.setup({})

Replace /absolute/path/to/rz with the path to your built binary (e.g. ~/GitHub/Resilient/resilient/target/release/rz). If your editor does not already know the resilient filetype, map .rz files to it before starting the client.

VS Code

Use the bundled vscode-extension/ or any generic LSP runner extension (e.g. Generic LSP Client). Point command at the rz binary with --lsp as the argument and set the language ID to resilient for .rz files.

The vscode-extension/ directory in the repo contains a minimal VS Code extension workspace; npm install && vsce package inside it produces an installable .vsix.

Semantic tokens

The server also serves textDocument/semanticTokens/full — editors that support semantic highlighting will color keywords, literals, type names, and function calls distinctly beyond what syntax highlighting alone provides.

Inlay hints

The server advertises textDocument/inlayHint support. Type hints are enabled by default for inferred let bindings and omitted function return types, including anonymous function literals. Disable those hints with the initialization option resilient.inlayHints.types: false.

Parameter hints for user-function call sites are opt-in. Enable them with resilient.inlayHints.parameters: true.

What’s next

  • Scope-aware local-variable completion.
  • Post-dot field completion for structs.
  • Finer-grained parser error positions.