Effect Language Service (TypeScript-Go)

A wrapper around TypeScript-Go that builds the Effect Language Service, providing Effect-TS diagnostics and quick fixes. This project targets Effect V4 (codename: "smol") primarily and also Effect V3.

Currently in Alpha

The TypeScript-Go version of the Effect LSP should be considered in Alpha. Expect breaking changes between releases and some missing features compared to previous version. Some of them are currently on hold due to not yet complete pipeline on the upstream TypeScript repository.

Installation

The setup of the TSGO version of the LSP can be performed via the command line interface:

npx @effect/tsgo setup

This will guide you through the installation process, which includes:

1. Adding the @effect/tsgo dependency to your project.
2. Configuring your tsconfig.json to use the Effect Language Service plugin.
3. Adjusting plugin options to your preference.
4. Hinting at any additional editor configuration needed to ensure the LSP is active.

[!NOTE] At the moment, you still need the standard native TypeScript install (@typescript/native-preview) alongside @effect/tsgo.

Diagnostic Status

Some diagnostics are off by default or have a default severity of suggestion, but you can always enable them or change their default severity in the plugin options.

➖ off by default, ❌ error, ⚠️ warning, 💬 message, 💡 suggestion, 🔧 quick fix available

Refactor Status

| Refactor | V3 | V4 | Notes | |----------|----|----|-------| | asyncAwaitToFn | ✅ | ✅ | Convert async/await to Effect.fn | | asyncAwaitToFnTryPromise | ✅ | ✅ | Convert async/await to Effect.fn with Error ADT + tryPromise | | asyncAwaitToGen | ✅ | ✅ | Convert async/await to Effect.gen | | asyncAwaitToGenTryPromise | ✅ | ✅ | Convert async/await to Effect.gen with Error ADT + tryPromise | | debugPerformance | ❌ | ❌ | Insert performance timing debug comments | | effectGenToFn | ✅ | ✅ | Convert Effect.gen to Effect.fn | | functionToArrow | ✅ | ✅ | Convert function declaration to arrow function | | layerMagic | ✅ | ✅ | Auto-compose layers with correct merge/provide | | makeSchemaOpaque | ✅ | ✅ | Convert Schema to opaque type aliases | | makeSchemaOpaqueWithNs | ✅ | ✅ | Convert Schema to opaque types with namespace | | pipeableToDatafirst | ✅ | ✅ | Convert pipeable calls to data-first style | | removeUnnecessaryEffectGen | ✅ | ✅ | Remove redundant Effect.gen wrapper | | structuralTypeToSchema | ✅ | ✅ | Generate recursive Schema from type alias | | toggleLazyConst | ✅ | ✅ | Toggle lazy/eager const declarations | | togglePipeStyle | ✅ | ✅ | Toggle pipe(x, f) vs x.pipe(f) | | toggleReturnTypeAnnotation | ✅ | ✅ | Add/remove return type annotation | | toggleTypeAnnotation | ✅ | ✅ | Add/remove variable type annotation | | typeToEffectSchema | ✅ | ✅ | Generate Effect.Schema from type alias | | typeToEffectSchemaClass | ✅ | ✅ | Generate Schema.Class from type alias | | wrapWithEffectGen | ✅ | ✅ | Wrap expression in Effect.gen | | wrapWithPipe | ❌ | ✅ | Wrap selection in pipe(...) | | writeTagClassAccessors | ✅ | ➖ | Generate static accessors for Effect.Service/Tag classes |

Completion Status

| Completion | V3 | V4 | Notes | |------------|----|----|-------| | contextSelfInClasses | ✅ | ➖ | Context.Tag self-type snippets in extends clauses (V3-only) | | effectDataClasses | ✅ | ✅ | Data class constructor snippets in extends clauses | | effectSchemaSelfInClasses | ✅ | ✅ | Schema/Model class constructor snippets in extends clauses | | effectSelfInClasses | ✅ | ➖ | Effect.Service/Effect.Tag self-type snippets in extends clauses (V3-only) | | genFunctionStar | ✅ | ✅ | gen(function*(){}) snippet when dot-accessing .gen on objects with callable gen property | | effectCodegensComment | ✅ | ✅ | @effect-codegens directive snippet in comments with codegen name choices | | effectDiagnosticsComment | ✅ | ✅ | @effect-diagnostics / @effect-diagnostics-next-line directive snippets in comments | | rpcMakeClasses | ✅ | ➖ | Rpc.make constructor snippet in extends clauses (V3-only) | | schemaBrand | ✅ | ➖ | brand("varName") snippet when dot-accessing Schema in variable declarations (V3-only) | | serviceMapSelfInClasses | ✅ | ✅ | Service map self-type snippets in extends clauses |

Codegen Status

| Codegen | V3 | V4 | Notes | |---------|----|----|-------| | accessors | ❌ | ❌ | Generate Service accessor methods from comment directive | | annotate | ❌ | ❌ | Generate type annotations from comment directive | | typeToSchema | ❌ | ❌ | Generate Schema from type alias comment directive |

Rename Status

| Rename | V3 | V4 | Notes | |--------|----|----|-------| | keyStrings | ❌ | ❌ | Extend rename to include key string literals in Effect classes |

Best Practices

Relationship to Official TypeScript-Go (tsgo)

Effect-tsgo is a superset of the official TypeScript-Go — it embeds a pinned version of tsgo with a small patch set on top and adds the Effect language service. This means effect-tsgo provides all standard TypeScript-Go functionality plus Effect-specific diagnostics, quick fixes, and refactors.

Use effect-tsgo instead of tsgo, not alongside it. Running both in parallel will produce duplicate diagnostics and degrade editor performance. Configure your editor to use effect-tsgo as your sole TypeScript language server.

Version Pinning

Each release of effect-tsgo is built against a specific upstream tsgo commit. The pinned commit is recorded in flake.nix (typescript-go-src). When upstream tsgo releases new features or fixes, effect-tsgo will adopt them in a subsequent release after validating compatibility with the Effect diagnostics layer.

When to Upgrade

• Upgrade effect-tsgo when a new release includes upstream tsgo fixes you need or new Effect diagnostics you want.
• There is no need to track upstream tsgo releases separately — effect-tsgo is the single binary to manage.

Plugin Options

{
  "compilerOptions": {
    "plugins": [
      {
        "name": "@effect/language-service",
        // Controls Effect refactors. (default: true)
        "refactors": true,
        // Controls Effect diagnostics. (default: true)
        "diagnostics": true,
        // When false, suggestion-level Effect diagnostics are omitted from tsc CLI output. (default: true)
        "includeSuggestionsInTsc": true,
        // Controls Effect quickinfo. (default: true)
        "quickinfo": true,
        // Controls Effect completions. (default: true)
        "completions": true,
        // Enables additional debug-only Effect language service output. (default: false)
        "debug": false,
        // Controls Effect goto references support. (default: true)
        "goto": true,
        // Controls Effect rename helpers. (default: true)
        "renames": true,
        // When true, suggestion diagnostics do not affect the tsc exit code. (default: true)
        "ignoreEffectSuggestionsInTscExitCode": true,
        // When true, warning diagnostics do not affect the tsc exit code. (default: false)
        "ignoreEffectWarningsInTscExitCode": false,
        // When true, error diagnostics do not affect the tsc exit code. (default: false)
        "ignoreEffectErrorsInTscExitCode": false,
        // When true, disabled diagnostics are still processed so directives can re-enable them. (default: false)
        "skipDisabledOptimization": false,
        // Mermaid rendering service for layer graph links. Accepts mermaid.live, mermaid.com, or a custom URL. (default: "mermaid.live")
        "mermaidProvider": "mermaid.live",
        // When true, suppresses external Mermaid links in hover output. (default: false)
        "noExternal": false,
        // How many levels deep the layer graph extraction follows symbol references. (default: 0)
        "layerGraphFollowDepth": 0,
        // When true, suppresses redundant return-type inlay hints on supported Effect generator functions. (default: false)
        "inlays": false,
        // Package names that should prefer namespace imports. (default: [])
        "namespaceImportPackages": [],
        // Package names that should prefer barrel named imports. (default: [])
        "barrelImportPackages": [],
        // Package-level import aliases keyed by package name. (default: {})
        "importAliases": {},
        // Controls whether named reexports are followed at package top-level. (default: "ignore")
        "topLevelNamedReexports": "ignore",
        // Configures key pattern formulas for the deterministicKeys rule. (default: [{"target":"service","pattern":"default","skipLeadingPath":["src/"]},{"target":"custom","pattern":"default","skipLeadingPath":["src/"]}])
        "keyPatterns": [
          {
            "target": "service",
            "pattern": "default",
            "skipLeadingPath": [
              "src/"
            ]
          },
          {
            "target": "custom",
            "pattern": "default",
            "skipLeadingPath": [
              "src/"
            ]
          }
        ],
        // Enables matching constructors with @effect-identifier annotations. (default: false)
        "extendedKeyDetection": false,
        // Minimum number of contiguous pipeable transformations to trigger missedPipeableOpportunity. (default: 2)
        "pipeableMinArgCount": 2,
        // Package names allowed to have multiple versions without triggering duplicatePackage. (default: [])
        "allowedDuplicatedPackages": [],
        // Controls which effectFnOpportunity quickfix variants are offered. (default: ["span"])
        "effectFn": [
          "span"
        ],
        // Maps rule names to severity levels. Use {} to enable diagnostics with rule defaults. (default: {})
        "diagnosticSeverity": {},
        // Ordered per-file diagnostic option overrides. (default: [{"include":["src/**/*.ts"],"options":{"diagnosticSeverity":{"floatingEffect":"error"}}}])
        "overrides": [
          {
            "include": [
              "src/**/*.ts"
            ],
            "options": {
              "diagnosticSeverity": {
                "floatingEffect": "error"
              }
            }
          }
        ]
      }
    ]
  }
}