The type for RNG keys.

key seed is a normalized 31-bit non-negative key derived from seed.

split ?n k deterministically derives n subkeys from k.

n defaults to 2.

fold_in k data mixes data into k and returns the derived key.

to_int k is k as an integer.

next_key () returns a fresh subkey from the current RNG scope.

Inside a run or with_key block, each call returns a deterministically derived key. Outside any scope, falls back to a domain-local auto-seeded generator (convenient but non-reproducible).

Two calls to next_key () always return different keys.

run ~seed f executes f in an RNG scope seeded by seed.

Every next_key call within f returns a deterministically derived key. The same seed and the same sequence of next_key calls produce the same keys. Scopes nest: an inner run replaces the outer scope for its duration.

with_key k f executes f in an RNG scope initialized from k.

This is the explicit-key equivalent of run: useful when you have an existing key from a split and want to establish a scope for a sub-computation (e.g. in layer composition).