4 ms·

> You'll find that while maps are in theory lists of vector pair They aren't. When you seq over a map you get a list of MapEntry, like so: (clojure.lang.Map

• Anderkent 12y ago
  user=> (pr-str (seq {:a 1 :b 2})) "([:a 1] [:b 2])" user=> (vector? (first (seq {:a 1 :b 2}))) true It looks like a vector, it quacks like a vector...
  • eddieplan9 12y ago
    user=> (doc vector?) ------------------------- clojure.core/vector? ([x]) Return true if x implements IPersistentVector nil So `MapEntry` implements `IPersistentVector`, but is not a vector. It does not make sense to have an empty `MapEntry`, so IMHO the behavior implemented is valid.
    • Anderkent 12y ago
      'Hey, if I peek under the abstraction, it all makes sense'. Obviously. The code does what it's written to do. That doesn't make such leaky abstractions okay. `vector?` is, AFAIK, the way to check if something is a vector, and if empty doesn't work on some `vector?`s, then i can't trust it. empty mapentry returning nil is meh. If it returned an empty vector it'd be what you want 99% of the time.