nil/docs/features.md

Features

This incomplete list tracks noteble features currently implemented or planned.

• Goto definition. textDocument/definition

  • References to parameters, let and rec {} bindings.
  • Relative paths.

• Find references. textDocument/reference

  • Parameters, let and rec {} bindings.
  • With expression.

• Links. textDocument/documentLink

  • Links for relative and absolute paths.
  • Links for search paths like <nixpkgs>.
  • Links for URLs like "https://...", "http://..." and etc.
  • Links for flake references like "github:NixOS/nixpkgs".

• Code actions. textDocument/codeAction

  • Convert name = name; bindings to inherit.

• Completion. textDocument/completion

  • Builtin names.
    • With documentations.
  • Local bindings and rec-attrset fields.
  • Keywords.
  • Attrset fields.

• Diagnostics. textDocument/publishDiagnostics

  • Syntax errors.
  • Hard semantic errors reported as parse errors by Nix, like duplicated keys in attrsets.
  • Undefiend names.
  • Warnings of legacy syntax.
  • Warnings of unnecessary syntax.
  • Warnings of unused bindings, with and rec.
  • Client pulled diagnostics.
  • Custom filter

    • You can disable some diagnostic messages via LSP setting diagnostics.ignored, which accepts an array of ignored diagnostic code strings, eg. ["unused_binding","unused_with"]. The code of diagnostics is usually shows in parentheses together with the message.

      See documentations of your editor about how to set LSP settings.

• Expand selection. textDocument/selectionRange

• Renaming. textDocument/renamme, textDocument/prepareRename

  • Identifiers in parameters and bindings, from let, rec and non-rec attrsets.
  • Static string literal bindings.
  • Merged path-value binding names.
  • Names introduced by inherit.
  • Names used by inherit.
  • Conflict detection.
  • Rename to string literals.

• Semantic highlighting. textDocument/semanticTokens/{range,full}

  • Delta response. textDocument/semanticTokens/full/delta

  • ⚠️ Currently it has performance issue for large files. It may be slow to respond when editing all-packages.nix.

    coc.nvim doesn't enable semantic highlighting by default. You need to manually enable it in settings.

    // coc-settings.json
    {
      "semanticTokens": { "filetypes": ["nix"] }
    }
    

• Hover text. textDocument/hover.

  • Show kind of names.
  • Documentation for builtin names.

• File symbols with hierarchy (aka. outline). textDocument/documentSymbol

• File formatting.

  • Whole file formatting.
  • Range formatting.
  • On-type formatting.
  • External formatter.

    • Currently, an external formatter must be configured via LSP setting formatting.command to enable this functionality. It accepts null for disabled, or an non-empty array for the formatting command, eg. ["nixpkgs-fmt"] for nixpkgs-fmt. The command must read Nix code from stdin and print the formatted code to stdout.

      You might need to set other editor settings to enable format-on-save. Like, for coc.nvim,

      // coc-settings.json
      {
        "coc.preferences.formatOnSaveFiletypes": ["nix"]
      }
      

• Cross-file analysis.

• Multi-threaded.

  • Request cancellation. $/cancelRequest