Add flatMapToMap diagnostic (#760)

Author: mattiamanzati

.changeset/curvy-effects-map.md

@@ -0,0 +1,5 @@
+---
+"@effect/language-service": minor
+---
+
+Add the `flatMapToMap` style diagnostic, which suggests replacing `Effect.flatMap((value) => Effect.succeed(f(value)))` with `Effect.map((value) => f(value))`.

README.md

@@ -121,6 +121,7 @@ Some diagnostics are off by default or have a default severity of suggestion, bu
     <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>flatMapToMap</code></td><td>💡</td><td>🔧</td><td>Suggests using Effect.map instead of Effect.flatMap when the callback only wraps its result with Effect.succeed</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>
     <tr><td><code>missedPipeableOpportunity</code></td><td>➖</td><td>🔧</td><td>Enforces the use of pipeable style for nested function calls</td><td>✓</td><td>✓</td></tr>
     <tr><td><code>missingEffectServiceDependency</code></td><td>➖</td><td></td><td>Checks that Effect.Service dependencies satisfy all required layer inputs</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,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,unsafeEffectTypeAssertion,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,flatMapToMap,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,unsafeEffectTypeAssertion,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,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,unsafeEffectTypeAssertion,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,flatMapToMap,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,unsafeEffectTypeAssertion,unsupportedServiceAccessors|}:\${2|off,warning,error,message,suggestion|}$0",
     "isSnippet": true,
     "kind": "string",
     "name": "@effect-diagnostics-next-line",

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

@@ -0,0 +1,9 @@
+flatMapToMap_fix from 136 to 150
+flatMapToMap_skipNextLine from 136 to 150
+flatMapToMap_skipFile from 136 to 150
+flatMapToMap_fix from 294 to 308
+flatMapToMap_skipNextLine from 294 to 308
+flatMapToMap_skipFile from 294 to 308
+flatMapToMap_fix from 490 to 504
+flatMapToMap_skipNextLine from 490 to 504
+flatMapToMap_skipFile from 490 to 504

packages/harness-effect-v3/__snapshots__/diagnostics/flatMapToMap.ts.flatMapToMap_fix.from136to150.output

@@ -0,0 +1,43 @@
+// code fix flatMapToMap_fix  output for range 136 - 150
+import { Effect, pipe } from "effect"
+
+// Should trigger: pipeable style
+export const shouldTriggerPipeable = Effect.succeed(1).pipe(
+  Effect.map((n) => n + 1)
+)
+
+// Should trigger: pipe style with a block body
+export const shouldTriggerPipe = pipe(
+  Effect.succeed(1),
+  Effect.flatMap((n) => {
+    return Effect.succeed(n + 1)
+  })
+)
+
+// Should trigger: pipeable style with a function expression
+export const shouldTriggerFunctionExpression = Effect.succeed(1).pipe(Effect.flatMap(function(n) {
+  return Effect.succeed(n + 1)
+}))
+
+// Should NOT trigger: data-first calls are not piping transformations
+export const shouldNotTriggerDataFirst = Effect.flatMap(Effect.succeed(1), (n) => Effect.succeed(n + 1))
+
+// Should NOT trigger: callback returns another Effect operation
+export const shouldNotTriggerEffect = Effect.succeed(1).pipe(
+  Effect.flatMap((n) => Effect.log(n))
+)
+
+// Should NOT trigger: callback contains additional logic
+export const shouldNotTriggerLogic = Effect.succeed(1).pipe(
+  Effect.flatMap((n) => {
+    console.log(n)
+    return Effect.succeed(n + 1)
+  })
+)
+
+// Should NOT trigger: unrelated flatMap and succeed functions
+const unrelated = {
+  flatMap: <A, B>(value: A, f: (value: A) => B): B => f(value),
+  succeed: <A>(value: A): A => value
+}
+export const shouldNotTriggerUnrelated = unrelated.flatMap(1, (n) => unrelated.succeed(n + 1))

packages/harness-effect-v3/__snapshots__/diagnostics/flatMapToMap.ts.flatMapToMap_fix.from294to308.output

@@ -0,0 +1,43 @@
+// code fix flatMapToMap_fix  output for range 294 - 308
+import { Effect, pipe } from "effect"
+
+// Should trigger: pipeable style
+export const shouldTriggerPipeable = Effect.succeed(1).pipe(
+  Effect.flatMap((n) => Effect.succeed(n + 1))
+)
+
+// Should trigger: pipe style with a block body
+export const shouldTriggerPipe = pipe(
+  Effect.succeed(1),
+  Effect.map((n) => {
+    return n + 1
+  })
+)
+
+// Should trigger: pipeable style with a function expression
+export const shouldTriggerFunctionExpression = Effect.succeed(1).pipe(Effect.flatMap(function(n) {
+  return Effect.succeed(n + 1)
+}))
+
+// Should NOT trigger: data-first calls are not piping transformations
+export const shouldNotTriggerDataFirst = Effect.flatMap(Effect.succeed(1), (n) => Effect.succeed(n + 1))
+
+// Should NOT trigger: callback returns another Effect operation
+export const shouldNotTriggerEffect = Effect.succeed(1).pipe(
+  Effect.flatMap((n) => Effect.log(n))
+)
+
+// Should NOT trigger: callback contains additional logic
+export const shouldNotTriggerLogic = Effect.succeed(1).pipe(
+  Effect.flatMap((n) => {
+    console.log(n)
+    return Effect.succeed(n + 1)
+  })
+)
+
+// Should NOT trigger: unrelated flatMap and succeed functions
+const unrelated = {
+  flatMap: <A, B>(value: A, f: (value: A) => B): B => f(value),
+  succeed: <A>(value: A): A => value
+}
+export const shouldNotTriggerUnrelated = unrelated.flatMap(1, (n) => unrelated.succeed(n + 1))

packages/harness-effect-v3/__snapshots__/diagnostics/flatMapToMap.ts.flatMapToMap_fix.from490to504.output

@@ -0,0 +1,43 @@
+// code fix flatMapToMap_fix  output for range 490 - 504
+import { Effect, pipe } from "effect"
+
+// Should trigger: pipeable style
+export const shouldTriggerPipeable = Effect.succeed(1).pipe(
+  Effect.flatMap((n) => Effect.succeed(n + 1))
+)
+
+// Should trigger: pipe style with a block body
+export const shouldTriggerPipe = pipe(
+  Effect.succeed(1),
+  Effect.flatMap((n) => {
+    return Effect.succeed(n + 1)
+  })
+)
+
+// Should trigger: pipeable style with a function expression
+export const shouldTriggerFunctionExpression = Effect.succeed(1).pipe(Effect.map(function(n) {
+  return n + 1
+}))
+
+// Should NOT trigger: data-first calls are not piping transformations
+export const shouldNotTriggerDataFirst = Effect.flatMap(Effect.succeed(1), (n) => Effect.succeed(n + 1))
+
+// Should NOT trigger: callback returns another Effect operation
+export const shouldNotTriggerEffect = Effect.succeed(1).pipe(
+  Effect.flatMap((n) => Effect.log(n))
+)
+
+// Should NOT trigger: callback contains additional logic
+export const shouldNotTriggerLogic = Effect.succeed(1).pipe(
+  Effect.flatMap((n) => {
+    console.log(n)
+    return Effect.succeed(n + 1)
+  })
+)
+
+// Should NOT trigger: unrelated flatMap and succeed functions
+const unrelated = {
+  flatMap: <A, B>(value: A, f: (value: A) => B): B => f(value),
+  succeed: <A>(value: A): A => value
+}
+export const shouldNotTriggerUnrelated = unrelated.flatMap(1, (n) => unrelated.succeed(n + 1))

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

@@ -0,0 +1,8 @@
+Effect.flatMap
+5:2 - 5:16 | 2 | `Effect.map` expresses this success-value transformation more directly than `Effect.flatMap` followed by `Effect.succeed`.    effect(flatMapToMap)
+
+Effect.flatMap
+11:2 - 11:16 | 2 | `Effect.map` expresses this success-value transformation more directly than `Effect.flatMap` followed by `Effect.succeed`.    effect(flatMapToMap)
+
+Effect.flatMap
+17:70 - 17:84 | 2 | `Effect.map` expresses this success-value transformation more directly than `Effect.flatMap` followed by `Effect.succeed`.    effect(flatMapToMap)

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

@@ -0,0 +1,42 @@
+import { Effect, pipe } from "effect"
+
+// Should trigger: pipeable style
+export const shouldTriggerPipeable = Effect.succeed(1).pipe(
+  Effect.flatMap((n) => Effect.succeed(n + 1))
+)
+
+// Should trigger: pipe style with a block body
+export const shouldTriggerPipe = pipe(
+  Effect.succeed(1),
+  Effect.flatMap((n) => {
+    return Effect.succeed(n + 1)
+  })
+)
+
+// Should trigger: pipeable style with a function expression
+export const shouldTriggerFunctionExpression = Effect.succeed(1).pipe(Effect.flatMap(function(n) {
+  return Effect.succeed(n + 1)
+}))
+
+// Should NOT trigger: data-first calls are not piping transformations
+export const shouldNotTriggerDataFirst = Effect.flatMap(Effect.succeed(1), (n) => Effect.succeed(n + 1))
+
+// Should NOT trigger: callback returns another Effect operation
+export const shouldNotTriggerEffect = Effect.succeed(1).pipe(
+  Effect.flatMap((n) => Effect.log(n))
+)
+
+// Should NOT trigger: callback contains additional logic
+export const shouldNotTriggerLogic = Effect.succeed(1).pipe(
+  Effect.flatMap((n) => {
+    console.log(n)
+    return Effect.succeed(n + 1)
+  })
+)
+
+// Should NOT trigger: unrelated flatMap and succeed functions
+const unrelated = {
+  flatMap: <A, B>(value: A, f: (value: A) => B): B => f(value),
+  succeed: <A>(value: A): A => value
+}
+export const shouldNotTriggerUnrelated = unrelated.flatMap(1, (n) => unrelated.succeed(n + 1))