got a response from borkdude here, unclear how to proceed though - how to pass a namespace? https://clojurians.slack.com/archives/C015LCR9MHD/p1663501053285409

you can pass in the normal sci-options via :malli.core/sci-options. what ever sci accepts, is accepted here too:

(m/validate
 [:fn '(fn [arg] (malli.impl.util/-invalid? arg))]
 ::m/invalid
 {::m/sci-options {:namespaces {'malli.impl.util {'-invalid? malli.impl.util/-invalid?}}}})
; => true

sci readme seems to have tips and helpers on how to bind multiple things at once.

specifically in my case, how can i add my custom fn get-num-cpu?

(defn get-num-cpus []
  (-> (Runtime/getRuntime) .availableProcessors))

(m/validate
 [:fn '(fn [arg] (= arg (get-num-cpus)))]
 10
 {::m/sci-options {:namespaces {'user {'get-num-cpus get-num-cpus}}}})
; => true

does that solve the issue?

but, do you need sci here?

thanks tommi! testing, getting back to you soon

hmm, i thought i did. don't i? i need to calculate the value based on amount of available cpus

you could also just remove the ' and say #(hash-map :thread-count (* 5 (get-num-cpus)))

wait. i could do that? i thought you couldn't pass functions

m/eval takes any function or a source code. for the latter, it uses sci to interpret it.

you can’t store normal functions as data (over wire / db etc), but if you don’t need that, you don’t have to use sci.

and i can put a fn under the :default key and it would work?

yes

(m/validate
 [:fn #(= % (get-num-cpus))]
 10)
; => true

amazing. i'm going to test that and get back to you. another question: what if i need to calculate the :default based on another key's input?

not storing this as data

see this example, how can i avoid sci?

[:parallel-pull-count
      {:title       "Pull messages thread count"
       :description ""
       :default 1}
      pos-int?]
     [:ack-and-lease-extension-thread-count
      {:title       "ACK processing and lease extension thread count"
       :description ""
       ; immitate java-pubsub's default value
       ; 
       :default-fn '#(max 6 (* 2 (:parallel-pull-count %)))}
      pos-int?]]]])

currently, the transformation interceptors don’t see their parents, so, attaching a transformer into a map key -> just sees that key & it’s children. This could be changed, but would need an issue and some thinking on how to do that.

but, you can attach the default values into the :map itself -> in that case the default-fn sees the whole map.

yeah but in case the map was given by the user and one of the keys is missing, i want to support defaulting there as well

btw, just tried your suggestion and it doesn't work:

:default #(hash-map :thread-count (* 5 (get-num-cpus)))}

; (out) clojure.lang.ExceptionInfo: Invalid configuration {"parsing_errors" {:concurrency ["invalid type"]}}

what am i doing wrong?

the :default key is defined in the default-value-transformer and it should be a value, e.g. (hash-map :thread-count (* 5 (get-num-cpus))). the default-fn-value-transformer defines a key :default-fn which can be a function, e.g. #(hash-map :thread-count (* 5 (get-num-cpus))).

(m/decode
 [:map {:default {}}
  [:x {:default (get-num-cpus)} string?]
  [:y {:default-fn #(* (get-num-cpus) (:x %))} string?]]
 nil
 (mt/transformer
  (mt/default-value-transformer)
  (default-fn-value-transformer)))
; => {:x 10, :y 100}

so i should use default-fn then

I think so

testing

it works. thank you!

> currently, the transformation interceptors don’t see their parents, so, attaching a transformer into a map key -> just sees that key & it’s children. This could be changed, but would need an issue and some thinking on how to do that. Interesting. That’s just the issue I was struggling with 😅 Should I create an issue?

To be more specific, I’m trying to get the name in the key of a :map-of construct, and use it as a default for one of the values in a sub-map