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faster distinct: maintain seen items in a set

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* hy/core/language.hy: maintain the seen items in a set instead of a
  list in `distinct`. This is much faster for lookups.
This commit is contained in:
Abhishek L 2014-02-04 01:35:41 +05:30
parent e8dfe5bfb2
commit a41a3c7edc
1 changed files with 2 additions and 2 deletions
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4
hy/core/language.hy
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@ -75,12 +75,12 @@
(defn distinct [coll] (defn distinct [coll]
"Return a generator from the original collection with duplicates "Return a generator from the original collection with duplicates
removed" removed"
(let [[seen []] [citer (iter coll)]] (let [[seen (set)] [citer (iter coll)]]
(for* [val citer] (for* [val citer]
(if (not_in val seen) (if (not_in val seen)
(do (do
(yield val) (yield val)
(.append seen val)))))) (.add seen val))))))
(defn drop [count coll] (defn drop [count coll]
"Drop `count` elements from `coll` and yield back the rest" "Drop `count` elements from `coll` and yield back the rest"