Function cachedFunction

packages/effect/src/internal/effect/circular.ts:446–477

(
  f: (a: A) => Effect.Effect<B, E, R>,
  eq?: Equivalence<A>
)

/** @internal */
export const cachedFunction = <A, B, E, R>(
  f: (a: A) => Effect.Effect<B, E, R>,
  eq?: Equivalence<A>
): Effect.Effect<(a: A) => Effect.Effect<B, E, R>> => {
  return pipe(
    core.sync(() => MutableHashMap.empty<Key<A>, Deferred.Deferred<readonly [FiberRefsPatch.FiberRefsPatch, B], E>>()),
    core.flatMap(makeSynchronized),
    core.map((ref) => (a: A) =>
      pipe(
        ref.modifyEffect((map) => {
          const result = pipe(map, MutableHashMap.get(new Key(a, eq)))
          if (Option.isNone(result)) {
            return pipe(
              core.deferredMake<readonly [FiberRefsPatch.FiberRefsPatch, B], E>(),
              core.tap((deferred) =>
                pipe(
                  effect.diffFiberRefs(f(a)),
                  core.intoDeferred(deferred),
                  fiberRuntime.fork
                )
              ),
              core.map((deferred) => [deferred, pipe(map, MutableHashMap.set(new Key(a, eq), deferred))] as const)
            )
          }
          return core.succeed([result.value, map] as const)
        }),
        core.flatMap(core.deferredAwait),
        core.flatMap(([patch, b]) => pipe(effect.patchFiberRefs(patch), core.as(b)))
      )
    )
  )
}

/** @internal */
export const raceFirst = dual<