flatMapToMap

Suggests using Effect.map instead of Effect.flatMap when the callback only wraps its result with Effect.succeed

Property	Value
Category	Style
Default severity	suggestion
Fixable	Yes
Effect versions	v3, v4
Diagnostic codes	TS377100
Language Service name	flatMapToMap
Oxlint name	effecttsgo/flat-map-to-map

Preview

import { Effect } from "effect"

const program = Effect.succeed(1).pipe(
  Effect.flatMap((value) => Effect.succeed(value + 1))
/**
  ^^^^^^^^^^^^^^ effecttsgo(flat-map-to-map): `Effect.map` expresses this success-value transformation more directly than `Effect.flatMap` followed by `Effect.succeed`.
*/
)

Language Service Configuration

See the Language Service setup guide for installation instructions.

{
  "$schema": "./node_modules/@effect/tsgo/schema.json",
  "compilerOptions": {
    "plugins": [
      {
        "name": "@effect/language-service",
        "diagnosticSeverity": {
          "flatMapToMap": "warning"
        }
      }
    ]
  }
}

Oxlint Configuration

See the Oxlint setup guide for installation and patching instructions.

{
  "$schema": "./node_modules/@effect/tsgo/oxlint-schema.json",
  "options": {
    "typeAware": true
  },
  "plugins": ["effecttsgo"],
  "rules": {
    "effecttsgo/flat-map-to-map": "warn"
  }
}