Array.flatten and pipe losing type information, inducing run time crash

[FredericEspiau]

What version of Effect is running?

3.19.13

What steps can reproduce the bug?

Not sure you can reproduce the bug with this but the situation is similar to the one I describe here, also I propose a solution at the end of this message.

declare const arg1: Effect.Effect<
  void,
  Error1 | Error2,
  Requirement1 | Requirement2
>;

declare const arg2: Effect.Effect<
  void,
  Error1 | Error2,
  Requirement1 | Requirement2 | Requirement3
>

const arg1BeforeArg2 = pipe(
    [
      arg1,
      arg2
    ],
    Array.flatten,
  );

const arg2BeforeArg1 = pipe(
    [
      arg2,
      arg1
    ],
    Array.flatten,
  );

What is the expected behavior?

Same signature for both arg1BeforeArg2 and arg2BeforeArg1

arg1BeforeArg2;
// ^
// Effect.Effect<
//   void,
//   Error1 | Error2,
//   Requirement1 | Requirement2 | Requirement3
// >

arg2BeforeArg1;
// ^
// Effect.Effect<
//   void,
//   Error1 | Error2,
//   Requirement1 | Requirement2 | Requirement3
// >

What do you see instead?

arg1BeforeArg2;
// ^
// Effect.Effect<
//   void,
//   Error1 | Error2,
//   Requirement1 | Requirement2
// >

arg1BeforeArg2;
// ^
// Effect.Effect<
//   void,
//   Error1 | Error2,
//   Requirement1 | Requirement2 | Requirement3
// >

The order of the items in the array shouldn't change the union type for Requirements.

Of course, this lead to a runtime error as we couldn't know that we were supposed to provide Requirement3 as the type system wasn't aware of it

Additional information

I was able to make it work by changing the type returned by the flatten function to be the one from this great library: https://github.com/inocan-group/inferred-types/blob/12da2b1282f2bab01f1e1d450aa87aa3bed85bcc/modules/types/src/lists/Flatten.ts

But it's really complex type 😅.

// packages/effect/src/Array.ts
import { Flatten } from 'inferred-types';

export const flatten: <const S extends ReadonlyArray<ReadonlyArray<any>>>(self: S) => Flatten<S> = flatMap(
  identity
) as any

Also by adding a const type parameter in pipe

// packages/effect/src/Pipeable.ts
export interface Pipeable {
  pipe<const A>(this: A): A
  pipe<const A, B = never>(this: A, ab: (_: A) => B): B
  pipe<const A, B = never, C = never>(this: A, ab: (_: A) => B, bc: (_: B) => C): C
  ...
}

// packages/effect/src/Function.ts
export function pipe<const A>(a: A): A
export function pipe<const A, B = never>(a: A, ab: (a: A) => B): B
export function pipe<const A, B = never, C = never>(
  a: A,
  ab: (a: A) => B,
  bc: (b: B) => C
): C
...

with both those changes, the type is inferred correctly.

[gcanti]

Please provide a reproducible example

[KhraksMamtsov]

Your example has type errors
This is my attempt to reproduce https://effect.website/play#f528a2eb0b09
Everything is fine