Hi,
I want to sort a set/map according to an ordering given by a seq of
elements - e.g.
(def some-order [:u :a :e :i :o])
(def some-order-fn (order-fn some-order))
(sorted-set-by some-order-fn :a :e :i :o :u) ; --> #{:u :a :e :i :o}
This is what I came up with:
(defn order-fn [ks]
#(- (.indexOf ks %1)
(.indexOf ks %2)))
But then one may want to replace .indexOf for some other ord-function- like
this:
(defn order-fn
([ks] (order-fn ks #(.indexOf %1 %2)))
([ks ord-fn]
#(- (ord-fn ks %1)
(ord-fn ks %2))))
Now we may force the elements to be present in ks:
(defn order-fn
([ks] (order-fn ks #(.indexOf %1 %2)))
([ks ord-fn]
(letfn
[(-ord-fn [e]
(let [o (ord-fn ks e)]
(if (> o -1) o
(throw
(RuntimeException.
(format "'%s' not found in %s" e ks))))))]
#(compare (-ord-fn %1)
(-ord-fn %2)))))
Is there something like this in clojure.core already or a more elegant
implementation?
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