[API reference](https://evolu.dev/docs/api-reference) › [@evolu/common](https://evolu.dev/docs/api-reference/common) › [Schedule](https://evolu.dev/docs/api-reference/common/Schedule) › tapScheduleInput

```ts
function tapScheduleInput<Input>(
  f: (input: Input) => void,
): <Output>(schedule: Schedule<Output, Input>) => Schedule<Output, Input>;
```

Defined in: [packages/common/src/Schedule.ts:1447](https://github.com/evoluhq/evolu/blob/e7144e2bbe9069362b62dec1b64a8aa922b8f1b0/packages/common/src/Schedule.ts#L1447)

Executes a side effect for every input without altering the schedule.

Useful for logging errors during retry or monitoring what values are being
processed.

### Example

```ts
interface MyError extends Typed<string> {}

const retrySchedule: Schedule<Millis, MyError> = exponential("100ms");

// Log each error during retry
const logged = tapScheduleInput((error: MyError) => {
  console.log(`Retrying after error: ${error.type}`);
})(retrySchedule);

// Track retry reasons
const reasons: Array<string> = [];
const tracked = tapScheduleInput((error: MyError) => {
  reasons.push(error.type);
})(retrySchedule);
```