Skip to content

WIT Language Support

WIT (WebAssembly Interface Types) is the interface description language of the WebAssembly Component Model. Hexana 0.9 ships a full language implementation for .wit files.

Capabilities

Editing

  • Lexer + parser (WitParserDefinition) with a complete PSI tree.
  • Brace matcher (WitBraceMatcher).
  • Commenter (WitCommenter) — Cmd/Ctrl+/ line comments, block comments.
  • Folding (WitFoldingBuilder) — package, interface, world, record, variant, enum, and function bodies are foldable.
  • Breadcrumbs (WitBreadcrumbsProvider) — visible at the top of the editor when the caret is inside a nested declaration.

Highlighting

  • Syntax highlighter (WitSyntaxHighlighter) — colours keywords, identifiers, literals, comments, semicolons, punctuation.
  • Semantic keyword highlighter (WitSemanticKeywordHighlighter, registered with order="first") — distinguishes contextual keywords from regular identifiers.

Completion

Two completion contributors:

  • WitKeywordCompletionContributor — completes WIT keywords (interface, world, package, import, export, use, include, type, record, variant, enum, flags, resource, func, etc.) based on parser context.
  • WitGateCompletionContributor — completes @since, @unstable, @deprecated gates and their parameter names.

Inspections

Five inspections, all wired through HexanaBundle for translation:

Inspection Level Condition
WitEmptyDefinitionInspection ERROR An interface, world, or other definition is declared with no body.
WitWorldNameUniquenessInspection ERROR Two worlds with the same name in the same package.
WitMissingSemicolonInspection WARNING A statement is missing its terminating semicolon.
WitGateInspection ERROR Malformed gate (@since, @unstable, @deprecated) — bad arguments or invalid placement.
WitUseDeclarationInspection ERROR A use declaration is missing names.
  • Find Usages via WitFindUsagesHandlerFactory — reference-aware across files.
  • Goto Symbol via HexanaGotoSymbolContributor — every interface, world, record, variant, function, and type appears in Cmd/Ctrl+Alt+Shift+N.
  • Goto Related Symbols line-marker (WitGoToRelatedSymbolsProvider) — gutter icons that jump to related declarations (e.g. a use to the definition it imports).
  • Cross-file resolve through WitComponentIndex plus the built-in WIT type definitions seeded by WitBuiltInDefinitionsContributor (indexedRootsProvider).

Rename and refactor

  • Rename input validator (WitRenameInputValidator) — rejects names that would violate WIT identifier rules.
  • Element manipulators for WitHandle, WitUsePath, WitUseNamesItem, WitIncludeNamesItem — the platform uses these to perform safe in-place rewrites during Rename, Move, and Inline.

Formatting

  • Formatter (WitFormattingBuilderModel) — applied by Reformat Code (Cmd/Ctrl+Alt+L).
  • Line-wrap strategy (WitLineWrapPositionStrategy) — controls where the editor wraps long lines.
  • Code style settings — WitCodeStyleSettingsProvider and WitLanguageCodeStyleSettingsProvider register a WIT tab under Settings → Editor → Code Style with indent and wrapping options.

Documentation

  • Documentation provider (WitDocumentationProvider) — F1 / hover shows declaration kind, parent package, and any preceding /// doc comments.

How Hexana resolves WIT symbols

  1. Local lookup within the current file (interface, world, record fields, function parameters, type aliases).
  2. use and include resolution — follows use a:b/c.{x, y} to the named declarations in the imported package.
  3. WitComponentIndex — file-based index keyed by fully qualified WIT name (namespace:package/interface.symbol). Resolution falls back to this when the symbol is in a different file.
  4. Built-in types — WitBuiltInDefinitionsContributor registers a synthetic source root containing the WIT primitives (bool, u8–u64, s8–s64, f32, f64, char, string, list<T>, option<T>, result<T, E>, tuple<…>).

If resolution fails at every layer, the reference is highlighted as unresolved and a quick-fix may offer to create the missing declaration.

Limitations in 0.9

  • WIT formatting is conservative — it preserves existing whitespace where the formatter doesn't have an explicit rule, rather than aggressively reflowing.
  • No quick-fixes are wired for the five inspections in 0.9; inspections report problems but do not auto-correct.
  • Component-Model @gate checking validates syntax only; semver-comparison against an actual target version is not yet implemented.
  • Find Usages on a WIT symbol does not yet search across .wasm binaries that import / export it — that bridge is on the roadmap.

See also