Comfy Cats Effect room. Ask questions. Rant about config file formats. Be nice!
you need to pass the
Ref around, and flatMap to seal the region of sharing
it's similar, you pass the inner F around, in all the places you need memoisation
everything you flatMap the outer one, you create a one region of memoisation
The outer
The inner
F[F[A]] is "create shared state to store memoization"The inner
F[A] is "read or populate the shared memoization state"
If you flatten it, you get "create shared state for memoization, then immediately populate it, and discard the access to the state"
like, it should be capitalized
Real Stupid Question
I've been coming at cats piecemeal, and the one thing I never really see explained is F[_]
I believe that it is supposed to be some sort of typed function but am not really sure enough to stake my life one it
am I correct, and if not, where can I become less stupid about this in the future?
do you want to know what
F[_] means in terms of language feature
or the point of the pattern? (and what the pattern is, how it works)
have you ever heard the word
kind?
in the context of type systems, of course :smile:
and in short
F[_] is a higher kinded type parameter
but we can make it more precise if you want
whoops, already started :)
no need to backtrack now
you have types of kind
* (pronounced star, or type)
these are types that don't need any extra information
e.g.
Int String Option[Int], Option[List[Either[String, Int]]] etc
but some types do need extra information