I would think ':b' could be in square brackets: [:a {:x "s"} [:b]], but it doesn't work, i'd like to be able to nest :cat/n

(-> [:cat
       [:enum :a]
       [:map [:x string?]]
       [:cat [:enum :b]]]
      (mc/explain
        [:a {:x "s"} :b])
      (me/humanize))

@joel380 from the README:

As all these examples show, the "seqex" operators take any non-seqex child schema to mean a sequence of one element that matches that schema. To force that behaviour for a seqex child :schema can be used:

(m/validate
  [:cat [:= :names] [:schema [:* string?]] [:= :nums] [:schema [:* number?]]]
  [:names ["a" "b"] :nums [1 2 3]])
; => true

;; whereas
(m/validate
  [:cat [:= :names] [:* string?] [:= :nums] [:* number?]]
  [:names "a" "b" :nums 1 2 3]) 
; => true

e.g.

[:cat
 [:enum :a]
 [:map [:x string?]]
 [:schema [:cat [:enum :b]]]]

@emccue fixed in master. Also, you don’t need the malli.instrument/collect!, malli.dev/start! calls that.

Question, is it possible to add sci options on a custom decoder, or any ability to set sci options globally?

Hi! How can I check if x satisfies the protocol y in malli metadata schema?

silly-hacky-var-watching-diy-horror:

(defn plus1
  "adds 1 to number"
  {:malli/schma [:=> [:cat :int] :int]}
  [x] (inc x))

(add-watch #'plus1 ::watch (fn [_ v _ _] (future (println v "=>" (-> v meta :malli/schema)))))

(defn plus1
  "adds 1 to number"
  {:malli/schema [:=> [:cat [:int {:min 0}]] :int]}
  [x] (inc x))
; =prints=> #'user/plus1 => [:=> [:cat [:int {:min 0}]] :int]

if that could be made robust, could just re-define schmatized vars and the clj-kondo + instrumentation would follow instantly.

ideas welcome (asked on #clojure too)

well, if it needs to be "scheduled to fetch later" you could have something like

(defn schedule-to-refresh 
  [var]
  (set! some-flag-another-thread-is-waiting-on true)
  ;; Or
  (.push some-array-blocking-queue-another-thread-is-waiting-on ...))

(add-watch #'plus1 
  (fn [_ v _ _]
    (schedule-to-refresh v)))

so at least you don't necessarily interact with the future threadpool

and it isn't a race condition

@ikitommi thanks for the humanize buffs 🙂