The functions get-in, assoc-in, update-in are really useful. Just
wanted to share a thoughts.
user=> (def m {:a {:b {:c 10 :c1 20} :b1 90} :a1 100})
#'user/m
1. Lets see the behavior of these functions in the corner case of
empty keyseq:
user=> (get-in m [])
{:a {:b {:c 10, :c1 20}, :b1 90}, :a1 100}
user=> (assoc-in m [] 42)
{nil 42, :a {:b {:c 10, :c1 20}, :b1 90}, :a1 100}
user=> (update-in m [] assoc :a2 42)
{nil {:a2 42}, :a {:b {:c 10, :c1 20}, :b1 90}, :a1 100}
get-in, assoc-in pretty much behave the way I would expect them to but
update-in is wierd especially considering get-in's output.
How about this:
user=> (update-in-2 m [] assoc :a2 42)
{:a2 42, :a {:b {:c 10, :c1 20}, :b1 90}, :a1 100}
(defn update-in-2
[m ks f & args]
(if (= 0 (count ks))
(apply f m args)
(let [[k & ks] ks]
(assoc m k
(apply update-in-2 (get m k) ks f args)))))
2. There's no dissoc-in ! With the above definition of update-in-2,
dissoc-in is simply:
(defn dissoc-in [m ks] (update-in-2 m (butlast ks) dissoc (last ks)))
Even assoc-in is simply:
(defn assoc-in [m ks v] (update-in-2 m (butlast ks) assoc (last ks)
v))
Can we please have dissoc-in in core.
- Thanks
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