Add Effect.map + Effect.flatten diagnostic

.changeset/fair-comics-march.md

@@ -0,0 +1,16 @@
+---
+"@effect/language-service": minor
+---
+
+Add the `effectMapFlatten` style diagnostic for `Effect.map(...)` immediately followed by `Effect.flatten` in pipe flows.
+
+Example:
+
+```ts
+import { Effect } from "effect"
+
+const program = Effect.succeed(1).pipe(
+  Effect.map((n) => Effect.succeed(n + 1)),
+  Effect.flatten
+)
+```

README.md

@@ -114,6 +114,7 @@ Some diagnostics are off by default or have a default severity of suggestion, bu
     <tr><td><code>deterministicKeys</code></td><td>➖</td><td>🔧</td><td>Enforces deterministic naming for service/tag/error identifiers based on class names</td><td>✓</td><td>✓</td></tr>
     <tr><td><code>effectDoNotation</code></td><td>➖</td><td></td><td>Suggests using Effect.gen or Effect.fn instead of the Effect.Do notation helpers</td><td>✓</td><td>✓</td></tr>
     <tr><td><code>effectFnOpportunity</code></td><td>💡</td><td>🔧</td><td>Suggests using Effect.fn for functions that returns an Effect</td><td>✓</td><td>✓</td></tr>
+    <tr><td><code>effectMapFlatten</code></td><td>💡</td><td></td><td>Suggests using Effect.flatMap instead of Effect.map followed by Effect.flatten in piping flows</td><td>✓</td><td>✓</td></tr>
     <tr><td><code>effectMapVoid</code></td><td>💡</td><td>🔧</td><td>Suggests using Effect.asVoid instead of Effect.map(() =&gt; void 0), Effect.map(() =&gt; undefined), or Effect.map(() =&gt; {})</td><td>✓</td><td>✓</td></tr>
     <tr><td><code>effectSucceedWithVoid</code></td><td>💡</td><td>🔧</td><td>Suggests using Effect.void instead of Effect.succeed(undefined) or Effect.succeed(void 0)</td><td>✓</td><td>✓</td></tr>
     <tr><td><code>importFromBarrel</code></td><td>➖</td><td>🔧</td><td>Suggests importing from specific module paths instead of barrel exports</td><td>✓</td><td>✓</td></tr>

packages/harness-effect-v3/__snapshots__/completions.test.ts.snap

@@ -248,7 +248,7 @@ exports[`Completion effectDataClasses > effectDataClasses_directImportTaggedErro
 exports[`Completion effectDiagnosticsComment > effectDiagnosticsComment.ts at 2:5 1`] = `
 [
   {
-    "insertText": "@effect-diagnostics \${1|anyUnknownInErrorContext,asyncFunction,catchAllToMapError,catchUnfailableEffect,classSelfMismatch,cryptoRandomUUID,cryptoRandomUUIDInEffect,deterministicKeys,duplicatePackage,effectDoNotation,effectFnIife,effectFnImplicitAny,effectFnOpportunity,effectGenUsesAdapter,effectInFailure,effectInVoidSuccess,effectMapVoid,effectSucceedWithVoid,extendsNativeError,floatingEffect,genericEffectServices,globalConsole,globalConsoleInEffect,globalDate,globalDateInEffect,globalErrorInEffectCatch,globalErrorInEffectFailure,globalFetch,globalFetchInEffect,globalRandom,globalRandomInEffect,globalTimers,globalTimersInEffect,importFromBarrel,instanceOfSchema,layerMergeAllWithDependencies,lazyPromiseInEffectSync,leakingRequirements,missedPipeableOpportunity,missingEffectContext,missingEffectError,missingEffectServiceDependency,missingLayerContext,missingReturnYieldStar,missingStarInYieldEffectGen,multipleEffectProvide,nestedEffectGenYield,newPromise,nodeBuiltinImport,nonObjectEffectServiceType,outdatedApi,outdatedEffectCodegen,overriddenSchemaConstructor,preferSchemaOverJson,processEnv,processEnvInEffect,redundantSchemaTagIdentifier,returnEffectInGen,runEffectInsideEffect,schemaStructWithTag,schemaSyncInEffect,schemaUnionOfLiterals,scopeInLayerEffect,serviceNotAsClass,strictBooleanExpressions,strictEffectProvide,tryCatchInEffectGen,unknownInEffectCatch,unnecessaryArrowBlock,unnecessaryEffectGen,unnecessaryFailYieldableError,unnecessaryPipe,unnecessaryPipeChain,unsupportedServiceAccessors|}:\${2|off,warning,error,message,suggestion|}$0",
+    "insertText": "@effect-diagnostics \${1|anyUnknownInErrorContext,asyncFunction,catchAllToMapError,catchUnfailableEffect,classSelfMismatch,cryptoRandomUUID,cryptoRandomUUIDInEffect,deterministicKeys,duplicatePackage,effectDoNotation,effectFnIife,effectFnImplicitAny,effectFnOpportunity,effectGenUsesAdapter,effectInFailure,effectInVoidSuccess,effectMapFlatten,effectMapVoid,effectSucceedWithVoid,extendsNativeError,floatingEffect,genericEffectServices,globalConsole,globalConsoleInEffect,globalDate,globalDateInEffect,globalErrorInEffectCatch,globalErrorInEffectFailure,globalFetch,globalFetchInEffect,globalRandom,globalRandomInEffect,globalTimers,globalTimersInEffect,importFromBarrel,instanceOfSchema,layerMergeAllWithDependencies,lazyPromiseInEffectSync,leakingRequirements,missedPipeableOpportunity,missingEffectContext,missingEffectError,missingEffectServiceDependency,missingLayerContext,missingReturnYieldStar,missingStarInYieldEffectGen,multipleEffectProvide,nestedEffectGenYield,newPromise,nodeBuiltinImport,nonObjectEffectServiceType,outdatedApi,outdatedEffectCodegen,overriddenSchemaConstructor,preferSchemaOverJson,processEnv,processEnvInEffect,redundantSchemaTagIdentifier,returnEffectInGen,runEffectInsideEffect,schemaStructWithTag,schemaSyncInEffect,schemaUnionOfLiterals,scopeInLayerEffect,serviceNotAsClass,strictBooleanExpressions,strictEffectProvide,tryCatchInEffectGen,unknownInEffectCatch,unnecessaryArrowBlock,unnecessaryEffectGen,unnecessaryFailYieldableError,unnecessaryPipe,unnecessaryPipeChain,unsupportedServiceAccessors|}:\${2|off,warning,error,message,suggestion|}$0",
     "isSnippet": true,
     "kind": "string",
     "name": "@effect-diagnostics",
@@ -259,7 +259,7 @@ exports[`Completion effectDiagnosticsComment > effectDiagnosticsComment.ts at 2:
     "sortText": "11",
   },
   {
-    "insertText": "@effect-diagnostics-next-line \${1|anyUnknownInErrorContext,asyncFunction,catchAllToMapError,catchUnfailableEffect,classSelfMismatch,cryptoRandomUUID,cryptoRandomUUIDInEffect,deterministicKeys,duplicatePackage,effectDoNotation,effectFnIife,effectFnImplicitAny,effectFnOpportunity,effectGenUsesAdapter,effectInFailure,effectInVoidSuccess,effectMapVoid,effectSucceedWithVoid,extendsNativeError,floatingEffect,genericEffectServices,globalConsole,globalConsoleInEffect,globalDate,globalDateInEffect,globalErrorInEffectCatch,globalErrorInEffectFailure,globalFetch,globalFetchInEffect,globalRandom,globalRandomInEffect,globalTimers,globalTimersInEffect,importFromBarrel,instanceOfSchema,layerMergeAllWithDependencies,lazyPromiseInEffectSync,leakingRequirements,missedPipeableOpportunity,missingEffectContext,missingEffectError,missingEffectServiceDependency,missingLayerContext,missingReturnYieldStar,missingStarInYieldEffectGen,multipleEffectProvide,nestedEffectGenYield,newPromise,nodeBuiltinImport,nonObjectEffectServiceType,outdatedApi,outdatedEffectCodegen,overriddenSchemaConstructor,preferSchemaOverJson,processEnv,processEnvInEffect,redundantSchemaTagIdentifier,returnEffectInGen,runEffectInsideEffect,schemaStructWithTag,schemaSyncInEffect,schemaUnionOfLiterals,scopeInLayerEffect,serviceNotAsClass,strictBooleanExpressions,strictEffectProvide,tryCatchInEffectGen,unknownInEffectCatch,unnecessaryArrowBlock,unnecessaryEffectGen,unnecessaryFailYieldableError,unnecessaryPipe,unnecessaryPipeChain,unsupportedServiceAccessors|}:\${2|off,warning,error,message,suggestion|}$0",
+    "insertText": "@effect-diagnostics-next-line \${1|anyUnknownInErrorContext,asyncFunction,catchAllToMapError,catchUnfailableEffect,classSelfMismatch,cryptoRandomUUID,cryptoRandomUUIDInEffect,deterministicKeys,duplicatePackage,effectDoNotation,effectFnIife,effectFnImplicitAny,effectFnOpportunity,effectGenUsesAdapter,effectInFailure,effectInVoidSuccess,effectMapFlatten,effectMapVoid,effectSucceedWithVoid,extendsNativeError,floatingEffect,genericEffectServices,globalConsole,globalConsoleInEffect,globalDate,globalDateInEffect,globalErrorInEffectCatch,globalErrorInEffectFailure,globalFetch,globalFetchInEffect,globalRandom,globalRandomInEffect,globalTimers,globalTimersInEffect,importFromBarrel,instanceOfSchema,layerMergeAllWithDependencies,lazyPromiseInEffectSync,leakingRequirements,missedPipeableOpportunity,missingEffectContext,missingEffectError,missingEffectServiceDependency,missingLayerContext,missingReturnYieldStar,missingStarInYieldEffectGen,multipleEffectProvide,nestedEffectGenYield,newPromise,nodeBuiltinImport,nonObjectEffectServiceType,outdatedApi,outdatedEffectCodegen,overriddenSchemaConstructor,preferSchemaOverJson,processEnv,processEnvInEffect,redundantSchemaTagIdentifier,returnEffectInGen,runEffectInsideEffect,schemaStructWithTag,schemaSyncInEffect,schemaUnionOfLiterals,scopeInLayerEffect,serviceNotAsClass,strictBooleanExpressions,strictEffectProvide,tryCatchInEffectGen,unknownInEffectCatch,unnecessaryArrowBlock,unnecessaryEffectGen,unnecessaryFailYieldableError,unnecessaryPipe,unnecessaryPipeChain,unsupportedServiceAccessors|}:\${2|off,warning,error,message,suggestion|}$0",
     "isSnippet": true,
     "kind": "string",
     "name": "@effect-diagnostics-next-line",

packages/harness-effect-v3/__snapshots__/diagnostics/effectMapFlatten.ts.codefixes

@@ -0,0 +1,6 @@
+effectMapFlatten_skipNextLine from 180 to 194
+effectMapFlatten_skipFile from 180 to 194
+effectMapFlatten_skipNextLine from 343 to 357
+effectMapFlatten_skipFile from 343 to 357
+effectMapFlatten_skipNextLine from 522 to 536
+effectMapFlatten_skipFile from 522 to 536

packages/harness-effect-v3/__snapshots__/diagnostics/effectMapFlatten.ts.output

@@ -0,0 +1,8 @@
+Effect.flatten
+6:2 - 6:16 | 2 | `Effect.map` + `Effect.flatten` is the same as `Effect.flatMap` that expresses the same steps more directly.    effect(effectMapFlatten)
+
+Effect.flatten
+13:2 - 13:16 | 2 | `Effect.map` + `Effect.flatten` is the same as `Effect.flatMap` that expresses the same steps more directly.    effect(effectMapFlatten)
+
+Effect.flatten
+19:2 - 19:16 | 2 | `Effect.map` + `Effect.flatten` is the same as `Effect.flatMap` that expresses the same steps more directly.    effect(effectMapFlatten)

packages/harness-effect-v3/__snapshots__/diagnostics/effectMapFlatten_preview.ts.codefixes

@@ -0,0 +1,2 @@
+effectMapFlatten_skipNextLine from 203 to 217
+effectMapFlatten_skipFile from 203 to 217

packages/harness-effect-v3/__snapshots__/diagnostics/effectMapFlatten_preview.ts.output

@@ -0,0 +1,2 @@
+Effect.flatten
+7:2 - 7:16 | 0 | `Effect.map` + `Effect.flatten` is the same as `Effect.flatMap` that expresses the same steps more directly.    effect(effectMapFlatten)

packages/harness-effect-v3/examples/diagnostics/effectMapFlatten.ts

@@ -0,0 +1,38 @@
+import { Effect, pipe } from "effect"
+
+// Should trigger: pipeable style
+export const shouldTriggerPipeable = Effect.succeed(1).pipe(
+  Effect.map((n) => Effect.succeed(n + 1)),
+  Effect.flatten
+)
+
+// Should trigger: function pipe style
+export const shouldTriggerPipe = pipe(
+  Effect.succeed(1),
+  Effect.map((n) => Effect.succeed(n + 1)),
+  Effect.flatten
+)
+
+// Should trigger: preserve later steps in the flow
+export const shouldTriggerLongerFlow = Effect.succeed(1).pipe(
+  Effect.map((n) => Effect.succeed(n + 1)),
+  Effect.flatten,
+  Effect.map((n) => n * 2)
+)
+
+// Should NOT trigger: already using flatMap
+export const shouldNotTriggerFlatMap = Effect.succeed(1).pipe(
+  Effect.flatMap((n) => Effect.succeed(n + 1))
+)
+
+// Should NOT trigger: flatten is not immediately after map
+export const shouldNotTriggerSeparated = Effect.succeed(1).pipe(
+  Effect.map((n) => Effect.succeed(n + 1)),
+  Effect.tap(() => Effect.void),
+  Effect.flatten
+)
+
+// Should NOT trigger: no flatten step
+export const shouldNotTriggerWithoutFlatten = Effect.succeed(1).pipe(
+  Effect.map((n) => Effect.succeed(n + 1))
+)

packages/harness-effect-v3/examples/diagnostics/effectMapFlatten_preview.ts

@@ -0,0 +1,8 @@
+// @effect-diagnostics *:off
+// @effect-diagnostics effectMapFlatten:warning
+import { Effect } from "effect"
+
+export const preview = Effect.succeed(1).pipe(
+  Effect.map((n) => Effect.succeed(n + 1)),
+  Effect.flatten
+)

packages/harness-effect-v4/__snapshots__/completions.test.ts.snap

@@ -109,7 +109,7 @@ exports[`Completion effectDataClasses > effectDataClasses.ts at 4:35 1`] = `
 exports[`Completion effectDiagnosticsComment > effectDiagnosticsComment.ts at 2:5 1`] = `
 [
   {
-    "insertText": "@effect-diagnostics \${1|anyUnknownInErrorContext,asyncFunction,catchAllToMapError,catchUnfailableEffect,classSelfMismatch,cryptoRandomUUID,cryptoRandomUUIDInEffect,deterministicKeys,duplicatePackage,effectDoNotation,effectFnIife,effectFnImplicitAny,effectFnOpportunity,effectGenUsesAdapter,effectInFailure,effectInVoidSuccess,effectMapVoid,effectSucceedWithVoid,extendsNativeError,floatingEffect,genericEffectServices,globalConsole,globalConsoleInEffect,globalDate,globalDateInEffect,globalErrorInEffectCatch,globalErrorInEffectFailure,globalFetch,globalFetchInEffect,globalRandom,globalRandomInEffect,globalTimers,globalTimersInEffect,importFromBarrel,instanceOfSchema,layerMergeAllWithDependencies,lazyPromiseInEffectSync,leakingRequirements,missedPipeableOpportunity,missingEffectContext,missingEffectError,missingEffectServiceDependency,missingLayerContext,missingReturnYieldStar,missingStarInYieldEffectGen,multipleEffectProvide,nestedEffectGenYield,newPromise,nodeBuiltinImport,nonObjectEffectServiceType,outdatedApi,outdatedEffectCodegen,overriddenSchemaConstructor,preferSchemaOverJson,processEnv,processEnvInEffect,redundantSchemaTagIdentifier,returnEffectInGen,runEffectInsideEffect,schemaStructWithTag,schemaSyncInEffect,schemaUnionOfLiterals,scopeInLayerEffect,serviceNotAsClass,strictBooleanExpressions,strictEffectProvide,tryCatchInEffectGen,unknownInEffectCatch,unnecessaryArrowBlock,unnecessaryEffectGen,unnecessaryFailYieldableError,unnecessaryPipe,unnecessaryPipeChain,unsupportedServiceAccessors|}:\${2|off,warning,error,message,suggestion|}$0",
+    "insertText": "@effect-diagnostics \${1|anyUnknownInErrorContext,asyncFunction,catchAllToMapError,catchUnfailableEffect,classSelfMismatch,cryptoRandomUUID,cryptoRandomUUIDInEffect,deterministicKeys,duplicatePackage,effectDoNotation,effectFnIife,effectFnImplicitAny,effectFnOpportunity,effectGenUsesAdapter,effectInFailure,effectInVoidSuccess,effectMapFlatten,effectMapVoid,effectSucceedWithVoid,extendsNativeError,floatingEffect,genericEffectServices,globalConsole,globalConsoleInEffect,globalDate,globalDateInEffect,globalErrorInEffectCatch,globalErrorInEffectFailure,globalFetch,globalFetchInEffect,globalRandom,globalRandomInEffect,globalTimers,globalTimersInEffect,importFromBarrel,instanceOfSchema,layerMergeAllWithDependencies,lazyPromiseInEffectSync,leakingRequirements,missedPipeableOpportunity,missingEffectContext,missingEffectError,missingEffectServiceDependency,missingLayerContext,missingReturnYieldStar,missingStarInYieldEffectGen,multipleEffectProvide,nestedEffectGenYield,newPromise,nodeBuiltinImport,nonObjectEffectServiceType,outdatedApi,outdatedEffectCodegen,overriddenSchemaConstructor,preferSchemaOverJson,processEnv,processEnvInEffect,redundantSchemaTagIdentifier,returnEffectInGen,runEffectInsideEffect,schemaStructWithTag,schemaSyncInEffect,schemaUnionOfLiterals,scopeInLayerEffect,serviceNotAsClass,strictBooleanExpressions,strictEffectProvide,tryCatchInEffectGen,unknownInEffectCatch,unnecessaryArrowBlock,unnecessaryEffectGen,unnecessaryFailYieldableError,unnecessaryPipe,unnecessaryPipeChain,unsupportedServiceAccessors|}:\${2|off,warning,error,message,suggestion|}$0",
     "isSnippet": true,
     "kind": "string",
     "name": "@effect-diagnostics",
@@ -120,7 +120,7 @@ exports[`Completion effectDiagnosticsComment > effectDiagnosticsComment.ts at 2:
     "sortText": "11",
   },
   {
-    "insertText": "@effect-diagnostics-next-line \${1|anyUnknownInErrorContext,asyncFunction,catchAllToMapError,catchUnfailableEffect,classSelfMismatch,cryptoRandomUUID,cryptoRandomUUIDInEffect,deterministicKeys,duplicatePackage,effectDoNotation,effectFnIife,effectFnImplicitAny,effectFnOpportunity,effectGenUsesAdapter,effectInFailure,effectInVoidSuccess,effectMapVoid,effectSucceedWithVoid,extendsNativeError,floatingEffect,genericEffectServices,globalConsole,globalConsoleInEffect,globalDate,globalDateInEffect,globalErrorInEffectCatch,globalErrorInEffectFailure,globalFetch,globalFetchInEffect,globalRandom,globalRandomInEffect,globalTimers,globalTimersInEffect,importFromBarrel,instanceOfSchema,layerMergeAllWithDependencies,lazyPromiseInEffectSync,leakingRequirements,missedPipeableOpportunity,missingEffectContext,missingEffectError,missingEffectServiceDependency,missingLayerContext,missingReturnYieldStar,missingStarInYieldEffectGen,multipleEffectProvide,nestedEffectGenYield,newPromise,nodeBuiltinImport,nonObjectEffectServiceType,outdatedApi,outdatedEffectCodegen,overriddenSchemaConstructor,preferSchemaOverJson,processEnv,processEnvInEffect,redundantSchemaTagIdentifier,returnEffectInGen,runEffectInsideEffect,schemaStructWithTag,schemaSyncInEffect,schemaUnionOfLiterals,scopeInLayerEffect,serviceNotAsClass,strictBooleanExpressions,strictEffectProvide,tryCatchInEffectGen,unknownInEffectCatch,unnecessaryArrowBlock,unnecessaryEffectGen,unnecessaryFailYieldableError,unnecessaryPipe,unnecessaryPipeChain,unsupportedServiceAccessors|}:\${2|off,warning,error,message,suggestion|}$0",
+    "insertText": "@effect-diagnostics-next-line \${1|anyUnknownInErrorContext,asyncFunction,catchAllToMapError,catchUnfailableEffect,classSelfMismatch,cryptoRandomUUID,cryptoRandomUUIDInEffect,deterministicKeys,duplicatePackage,effectDoNotation,effectFnIife,effectFnImplicitAny,effectFnOpportunity,effectGenUsesAdapter,effectInFailure,effectInVoidSuccess,effectMapFlatten,effectMapVoid,effectSucceedWithVoid,extendsNativeError,floatingEffect,genericEffectServices,globalConsole,globalConsoleInEffect,globalDate,globalDateInEffect,globalErrorInEffectCatch,globalErrorInEffectFailure,globalFetch,globalFetchInEffect,globalRandom,globalRandomInEffect,globalTimers,globalTimersInEffect,importFromBarrel,instanceOfSchema,layerMergeAllWithDependencies,lazyPromiseInEffectSync,leakingRequirements,missedPipeableOpportunity,missingEffectContext,missingEffectError,missingEffectServiceDependency,missingLayerContext,missingReturnYieldStar,missingStarInYieldEffectGen,multipleEffectProvide,nestedEffectGenYield,newPromise,nodeBuiltinImport,nonObjectEffectServiceType,outdatedApi,outdatedEffectCodegen,overriddenSchemaConstructor,preferSchemaOverJson,processEnv,processEnvInEffect,redundantSchemaTagIdentifier,returnEffectInGen,runEffectInsideEffect,schemaStructWithTag,schemaSyncInEffect,schemaUnionOfLiterals,scopeInLayerEffect,serviceNotAsClass,strictBooleanExpressions,strictEffectProvide,tryCatchInEffectGen,unknownInEffectCatch,unnecessaryArrowBlock,unnecessaryEffectGen,unnecessaryFailYieldableError,unnecessaryPipe,unnecessaryPipeChain,unsupportedServiceAccessors|}:\${2|off,warning,error,message,suggestion|}$0",
     "isSnippet": true,
     "kind": "string",
     "name": "@effect-diagnostics-next-line",

packages/harness-effect-v4/__snapshots__/diagnostics/effectMapFlatten.ts.codefixes

@@ -0,0 +1,6 @@
+effectMapFlatten_skipNextLine from 180 to 194
+effectMapFlatten_skipFile from 180 to 194
+effectMapFlatten_skipNextLine from 343 to 357
+effectMapFlatten_skipFile from 343 to 357
+effectMapFlatten_skipNextLine from 522 to 536
+effectMapFlatten_skipFile from 522 to 536

packages/harness-effect-v4/__snapshots__/diagnostics/effectMapFlatten.ts.output

@@ -0,0 +1,8 @@
+Effect.flatten
+6:2 - 6:16 | 2 | `Effect.map` + `Effect.flatten` is the same as `Effect.flatMap` that expresses the same steps more directly.    effect(effectMapFlatten)
+
+Effect.flatten
+13:2 - 13:16 | 2 | `Effect.map` + `Effect.flatten` is the same as `Effect.flatMap` that expresses the same steps more directly.    effect(effectMapFlatten)
+
+Effect.flatten
+19:2 - 19:16 | 2 | `Effect.map` + `Effect.flatten` is the same as `Effect.flatMap` that expresses the same steps more directly.    effect(effectMapFlatten)

packages/harness-effect-v4/__snapshots__/diagnostics/effectMapFlatten_preview.ts.codefixes

@@ -0,0 +1,2 @@
+effectMapFlatten_skipNextLine from 203 to 217
+effectMapFlatten_skipFile from 203 to 217

packages/harness-effect-v4/__snapshots__/diagnostics/effectMapFlatten_preview.ts.output

@@ -0,0 +1,2 @@
+Effect.flatten
+7:2 - 7:16 | 0 | `Effect.map` + `Effect.flatten` is the same as `Effect.flatMap` that expresses the same steps more directly.    effect(effectMapFlatten)