(mount/swap-states {#'df-svc/fetch-schema-fn {:start #(constantly fn)}})

https://github.com/tolitius/mount/blob/master/README.md#swapping-states-with-states

yea, you would want a "function" in a swap-states map

What the difference is: a function returning a function in swap-states but a normal function in the actual state

I will paste what I have