@effect-ts/system/_src/Effect/flatten.ts

Effect-TS is a zero dependency set of libraries to write highly productive, purely functional TypeScript at scale.

// ets_tracing: off

import { identity } from "../Function/index.js"
import { chain_ } from "./core.js"
import type { Effect } from "./effect.js"

/**
 * Returns an effect that first executes the outer effect, and then executes
 * the inner effect, returning the value from the inner effect, and effectively
 * flattening a nested effect.
 */
export function flatten<R, E, R1, E1, A>(
  effect: Effect<R, E, Effect<R1, E1, A>>,
  __trace?: string
) {
  return chain_(effect, identity, __trace)
}