Function definition of Clojure built-ins: def vs defn
Why are some (many) of Clojure's built-in functions defined using `def`, not `defn`?

I know that `defn` is a shortcut for `def`, but I'm wondering if there's some other reason such as efficiency/readability/style considerations/bootstrapping.
Function definition of Clojure built-ins: def vs defn
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Why are some (many) of Clojure's built-in functions defined using `def`, not `defn`?

I know that `defn` is a shortcut for `def`, but I'm wondering if there's some other reason such as efficiency/readability/style considerations/bootstrapping.