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Adds transjuxt.

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Christophe Grand 2015-09-15 14:08:44 +02:00
parent 8e98bc0b2f
commit 77ca032c01
1 changed files with 15 additions and 0 deletions
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15
src/net/cgrand/xforms.clj
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@ -290,3 +290,18 @@
([acc] (zipmap keys (f acc))) ([acc] (zipmap keys (f acc)))
([acc x] (f acc x))))) ([acc x] (f acc x)))))
(defn just
"Reducing function that returns the first value or nil if none."
([] nil)
([x] x)
([_ x] (reduced x)))
(defn transjuxt
"Performs several transductions over coll at once. xforms-map can be a map or vector.
Returns a map with the same keyset as xforms-map (or a vector of same size as xforms-map)."
[xforms-map coll]
(let [rf (if (vector? xforms-map)
(apply juxt (map #(% just) xforms-map))
(apply juxt-map (sequence (comp (by-key (map #(% just))) cat) xforms-map)))]
(rf (clj/reduce rf (rf) coll))))