# filterEffect

Effectfully decides which Fx output values are emitted.

Each upstream value runs one predicate. `true` emits that value, `false` emits
none, and predicate failures join the output error channel. For a sequential
source the predicate is acknowledged before the next delivery, preserving
order; the input side is unchanged.

## Signatures

```ts
export declare const filterEffect: {
    <B, R3, E3>(f: (b: B) => Effect.Effect<boolean, E3, R3>): <A, E, R, E2, R2>(push: Push<A, E, R, B, E2, R2>) => Push<A, E, R, B, E2 | E3, R2 | R3>;
    <A, E, R, B, E2, R2, R3, E3>(push: Push<A, E, R, B, E2, R2>, f: (b: B) => Effect.Effect<boolean, E3, R3>): Push<A, E, R, B, E2 | E3, R2 | R3>;
};
```

## Why

Use this when an observed event needs an Effect service or fallible check before
it is visible downstream.

## Ownership and lifetime

Predicate effects run inside and are interrupted with the output subscription.
Their `E3` failures and `R3` services join the Fx channels. No separate queue or
persistent fiber is introduced.

## Examples

```ts
import { Effect } from "effect"
import * as Fx from "@typed/fx/Fx"
import * as Push from "@typed/fx/Push"
import * as Sink from "@typed/fx/Sink"

const push = Push.make(Sink.make(() => Effect.void, (_: string) => Effect.void), Fx.fromIterable([1, 2]))
const positive = Push.filterEffect(push, (n) => Effect.succeed(n > 0))
```