How fun! I was looking for classes defined within Clojure's core library via deftype, and noticed for the first time that in the pretty_writer.clj source file that is part of the clojure.pprint implementation, there is a macro called deftype created in there that is different than clojure.core/deftype. Fun!

ä

It’s possible I’m conflating it with another language but isn’t there a core function for filtering things with a map?

@jayzawrotny Maybe the map itself is the filter?

It would be for filtering other maps in a collection

It depends on your example. Keywords and maps implement IFn, so you can use them as a filter fn.

Right

(->> [{:color :blue
       :size :l}
      {:color :red
       :size :s}
      {:color :green
       :size :s}
      {:color :purple
       :size :s}]
     (filter #(where? % {:size :s})))

#(= :s (:size %))

I also have some submap? function in some tests but that's not in core

#(= (select-keys %2 (keys %1)) %1)

That’s what I went with noisesmith, I must have been thinking about the submap? predicate that I think Alex posted somewhere once.

In the spec tests

https://github.com/clojure/spec.alpha/blob/eb49d429e85b6878a61443e853be26092ff6e249/src/test/clojure/clojure/test_clojure/spec.clj#L17

I've been tweaking it for my tests: https://github.com/borkdude/clj-kondo/blob/ca947294b18df2b1049ceca5a29578cee89b037f/test/clj_kondo/test_utils.clj#L15