Provide access to construct a generator from Seed -> (a, Seed)

In Random we have:

type Generator a =
    Generator (Seed -> (a, Seed))

So if I have a way of doing Seed -> (a, Seed)), I should be able to make a Generator a.
Well not exactly.

I can do:

fromStep : (Seed -> ( a, Seed )) -> Generator a
fromStep step =
    Random.independentSeed |> Random.map (step >> Tuple.first)

The problem here is independantSeed goes through the extra work of creating a new seed, and then we throw out the seed after the generator is used.

There’s no way to use a seed and step, (generating a value) and returning the value and the next seed.

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