# subtract

Subtract a BigDecimal from the current state of a RefBigDecimal.

## Signatures

```ts
export declare const subtract: {
    (that: BigDecimal.BigDecimal): <E, R>(ref: RefBigDecimal<E, R>) => RefSubject.Computed<BigDecimal.BigDecimal, E, R>;
    <E, R>(ref: RefBigDecimal<E, R>, that: BigDecimal.BigDecimal): RefSubject.Computed<BigDecimal.BigDecimal, E, R>;
};
```

## Why

Subtract a BigDecimal from the current state of a RefBigDecimal. The operation remains attached
to the RefSubject's versioned state boundary.

## Ownership and lifetime

The subtract view retains no independent state. An Effect read samples the source once; Fx
observation follows later pushes and its observing Scope owns subscription cleanup.