let's say, I have a current implementation that lo...

# arrow

[ivanmorgillo]

let's say, I have a current implementation that looks like this:

suspend fun loadInt(key: String): Int?

The null is representing the absence of the value and that's why I was thinking about Either or Option, but then there is that problem.

How would you imagine a migration to IO?

Something like this would work?

fun loadInt(key: String): IO<Int>

[simon.vergauwen]

It’s all about shape and structure.

IO<None, A> could be a non wrapped version of suspend () -> A? where you can capture it as such and run it to A? as a suspend function.

[ivanmorgillo]

I guess I need more studying, because I'm not sure I understand the answer 😕

[simon.vergauwen]

Option<A> = None | Some<A>, or Option<A> is modelled by a object marker None that short-circuits and a marker for A that is biased.
IO<E, A> can model suspend () -> Option<A> with a object marker None (IO.Error<None>)that short-circuits and a marker for A that is biased (IO.Just)

[simon.vergauwen]

That way you can without additional wrapping consume A? safely into IO and run it later back to A? without additional wrapping in IO.