clojure - How to build data structure using nested calls to `map` -


i want build sequence of maps (the data structure) using nested calls map (the function). here's i'm doing

(defn point [x y]   {:x-coord x    :y-coord y})  (defn grid [rows columns]   (mapcat      (fn [x] map               (fn [y] (point x y))               (range columns))     (range rows)))

which compiles fine, doesn't work expect. expected call grid result in sequence of maps:

user=>(grid 2 2) ({:x-coord 0, :y-coord 0} {:x-coord 0, :y-coord 1} {:x-coord 1, :y-coord 0} {:x-coord 1, :y-coord 1})

but got sequence of ints:

user=> (grid 2 2) (0 1 0 1)

so question is, how can sequence want? and, why did particular sequence got?

you need call map. in way wrote inner map not being called. returning result of (range columns).

try this:

(defn grid [rows columns]   (mapcat (fn [x]              (map (fn [y] (point x y))                  (range columns)))           (range rows)))

you can make call point that: #(point x %). easier read way wrote.


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