Function mapKeys

mapKeys<K extends PropertyKey, V, K2 extends PropertyKey>(
record: Readonly<Record<K, V>>,
fn: (key: K, value: V) => K2,
): Record<K2, V>
Rewrite each key via fn; values are preserved. If fn produces the same key for multiple entries the later one wins (iteration order).

Dual API — works data-first or curried for use in pipe.
Type Parameters
- K extends PropertyKey
- V
- K2 extends PropertyKey
Parameters
- record: Readonly<Record<K, V>>
- fn: (key: K, value: V) => K2
Returns Record<K2, V>
Example
```
pipe(
    { firstName: "Ada", lastName: "Lovelace" },
    Records.mapKeys((k) => k.toUpperCase()),
  )
  // { FIRSTNAME: "Ada", LASTNAME: "Lovelace" }
```
- Defined in records/transform.ts:51
mapKeys<K extends PropertyKey, K2 extends PropertyKey, V = unknown>(
fn: (key: K, value: V) => K2,
): (record: Readonly<Record<K, V>>) => Record<K2, V>
Rewrite each key via fn; values are preserved. If fn produces the same key for multiple entries the later one wins (iteration order).

Dual API — works data-first or curried for use in pipe.
Type Parameters
- K extends PropertyKey
- K2 extends PropertyKey
- V = unknown
Parameters
- fn: (key: K, value: V) => K2
Returns (record: Readonly<Record<K, V>>) => Record<K2, V>
Example
```
pipe(
    { firstName: "Ada", lastName: "Lovelace" },
    Records.mapKeys((k) => k.toUpperCase()),
  )
  // { FIRSTNAME: "Ada", LASTNAME: "Lovelace" }
```
- Defined in records/transform.ts:55