I've been using Meikel's defnk macro a fair bit in some of my code. I have several functions that have sensible defaults that only need to be overridden occasionally, so keyword arguments fit the bill nicely.
Let's consider two (contrived) keyword fns. (use 'clojure.contrib.def) (defnk add [x :y 10 :z 20] (+ x y z)) (defnk nil-free? [a :b 1 :c 2] (every? (comp not nil?) [a b c])) There are several occasions I would like to use apply, and supply a map for the keyword arguments. For those of you with a Python background, it would work just like the ** operator. Let's call this function apply-map (a definition can be found here: http://gist.github.com/159324 ). You can use apply-map just like you would apply. (def useful-vec [:y 0]) (def useful-map {:y 0}) user=> (apply add 1 usefull-vec) 21 ;This could be used to apply setting from a user... user=>(apply-map add 1 useful-map) 21 Some more use cases: user=> (def test-map {:a "A" :b "B" :c "C"}) #'user/test-map user=> (vector test-map) [{:a "A", :b "B", :c "C"}] user=> (apply vector test-map) [[:a "A"] [:b "B"] [:c "C"]] user=> (apply-map vector test-map) [:a "A" :b "B" :c "C"] This helps with higher order functions ;This worked before, because Meikel is just awesome. user=>(map add [1 2 3]) (31 32 33) ;Slightly ugly, but it works... user=>(map #(apply-map add (first %) (second %)) [[1 {:z 0}] [2 {:y 0}] [3]]) (11 22 33) Similarly, this works for filter/remove ;Again, somewhat ugly... user=>(filter #(apply-map nil-free? (first %) (second %)) [[nil {}] [1 {:b nil}] [2]]) ([2]) This does NOT attempt to solve the problem of mixing keyword and variable length arguments. However, I think it is a step forward in making keyword arguments more useful in Clojure. Feedback? --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "Clojure" group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en -~----------~----~----~----~------~----~------~--~---
