Can't convert type Map to type Sequence

[jeroenvandijk]

Found in https://github.com/Convex-Dev/convex.cljc/blob/main/module/break/src/test/clj/convex/test/break/coll.clj#L1216

This comes up with mapcat, but eventually also related to what map does see #20

Again a bit confusing (for me) especially since both concat and map work with a map.

(concat {:a 1} {:b 2}) ;=> [[:a 1] [:b 2]]
(concat (vec {:a 1}) (vec {:b 2})) ;=> [[:a 1] [:b 2]]
(mapcat identity {:a 1}) ;=> error
;; Mapcat is implemented as => 
(apply concat (empty {}) (apply map identity {:a 1} [])) ;=> error

;; Eventually

(apply concat {} {}) ;=> ; ERROR [CAST]: Can't convert argument at position 3 (with type Map) to type Sequence

[mikera]

Currently apply requires a sequence as the last argument.

I am tempted to make it work on any data structure though? It doesn't seem problematic

[jeroenvandijk]

Nice, yeah I think it is helpful. I saw Convex-Dev/convex@fa24002 Is this also gonna work for sets and Index-es? Those were the other case in the tests. I think for sets it will be helpful. I came accross this while implementing the chess. For Index I don't know.