effectMapFlatten

Suggests using Effect.flatMap instead of Effect.map followed by Effect.flatten in piping flows

Property	Value
Category	Style
Default severity	suggestion
Fixable	No
Effect versions	v3, v4
Diagnostic codes	TS377086
Language Service name	effectMapFlatten
Oxlint name	effecttsgo/effect-map-flatten

Preview

import { Effect } from "effect"

export const preview = Effect.succeed(1).pipe(
  Effect.map((n) => Effect.succeed(n + 1)),
  Effect.flatten
/**
  ^^^^^^^^^^^^^^ effecttsgo(effect-map-flatten): `Effect.map` + `Effect.flatten` is the same as `Effect.flatMap` that expresses the same steps more directly.
*/
)

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": {
          "effectMapFlatten": "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/effect-map-flatten": "warn"
  }
}