# Parser.FlatMapTo

Binds a Parser and dependent mapping lambda for reuse.

## Signatures

```ts
interface FlatMapTo<F extends TypeFunction> extends TypeFunction {
    readonly return: InputOf<this> extends infer P extends Any ? FlatMap<P, F> : never;
}
```

## Why

Higher-order grammar can defer dependent parsing while fixing its first stage.

## Ownership and lifetime

TypeScript instantiates `FlatMapTo` while parsing a string-literal input; partial results and unconsumed text exist only in the resulting type.

## Property: return

Computes this type lambda's parse result for its current input.

## Property: return: Why

The local type-function protocol evaluates each parser combinator through this member without a parallel runtime object.

## Property: return: Ownership and lifetime

TypeScript evaluates `FlatMapTo.return` when the surrounding parser is applied; the associated result is erased and retains no input at runtime.