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comparison mtg/bk.clj @ 2:b4de894a1e2e

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initial import
author Robert McIntyre <rlm@mit.edu>
date Fri, 28 Oct 2011 00:03:05 -0700
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1:8d8278e09888 2:b4de894a1e2e
1 (ns mtg.frame)
2
3 ;; GENERALLY USEFUL FUNCTIONS
4
5 (defn assay "Takes x and a series of pred-value pairs. Returns a list of vals for which the corresponding preds are true of x." [x & pred-vals]
6 (reduce #(if ((first %2) x) (conj %1 (second %2))) '() pred-vals)
7 )
8 (defn alter-val "Applies f to the current value associated with each key, associating each key with the value returned." [m f & keys]
9 (map #(assoc m % (f (get m %))) keys))
10
11 (defn every-nth "Returns every nth member of coll. If n is not positive, returns an empty list." [n coll]
12 (if (<= n 0) '()
13 (take-while (comp not nil?) (map first (iterate #(nthnext % n) coll)))))
14
15
16
17
18
19 ;; FRAME MANIPULATION
20
21
22 (defn conj-key "Adds the xs to the seq associated with the given key." [map key & xs]
23 (assoc map key (apply conj (get map key []) xs)))
24
25 (defn update "Takes a frame and a sequence of key-fn pairs. Applies f to the current value associated with key, updating the current value with the result. Frames generate and store a unique id for each call to update."
26 [frame & kfs]
27 (let [id (gensym "up_")
28 keys (every-nth 2 kfs)
29 fns (every-nth 2 (rest kfs))]
30
31 ((reduce comp (map (fn[k f](fn[m](conj-key m k (list id f) )) keys fns))
32 (conj-key frame :*bindings* (map (fn [k f](list id k)) keys fns))
33 )
34 ))
35
36
37
38
39 (def *frame* (atom {:*bindings* '()}))