hi everybody, what's the way to spec something is a promise of some kind

not really any good way right now

I would focus on spec’ing the place where you deliver the value and receive the value

you could do

(s/def ::promise #(= (class %) (class (promise))))

you could put the class of the promise elsewhere if you wanted to avoid creating a promise each time you ran the predicate

I’m not sure there’s much value in checking just that something is a promise. I presume what is of interest is that it’s a promise that returns something that matches a spec

however, checking for that would require you to block waiting for the promise to be delivered

so I think you instead want to validate the spec at the point where you are already retrieving the value

or where you are delivering the value

thanks @joshjones @alexmiller

yeah I'm trying to spec a function return that returns a promise with an int?

since it's a :ret I'm not worried about instrument blocking on deref

I'm more interested in the doc aspect

Several times I've wanted to be able to spec "this should be an atom containing an X" so I feel the lack @jpmonettas -- but as @alexmiller says, a lot of the times where you would want this, spec would need to deref the container to check the value inside and that's not the correct semantics (it would block).

It would make me want to have the function return int, and instead call it in a future (which has the advantage that the caller controls both the wrapping and the dereference).

(since you don't mind the checker blocking on a deref to check the value anyway)

You can put a validator on the atom with a valid? check i guess

Wont help with gen tho

Golang is interesting for chan args, you can say "this arg is a chan of int that can only be take!en in that scope" etc

Chan args have a concept of "direction"

As do core.async chans via the port protocols

Yes it s very similar

xforms on chans might make specing them more tricky tho