# Specification: transducers.
(use ../support/harness)

(defspec "transducers / into"
  ["map xform"          "[2 3 4]"   "(into [] (map inc) [1 2 3])"]
  ["filter xform"       "[2 4]"     "(into [] (filter even?) [1 2 3 4])"]
  ["remove xform"       "[1 3]"     "(into [] (remove even?) [1 2 3 4])"]
  ["take xform"         "[1 2]"     "(into [] (take 2) [1 2 3 4])"]
  ["drop xform"         "[3 4]"     "(into [] (drop 2) [1 2 3 4])"]
  ["take-while xform"   "[1 2]"     "(into [] (take-while (fn [x] (< x 3))) [1 2 3 1])"]
  ["keep xform"         "[1 3]"     "(into [] (keep (fn [x] (if (odd? x) x nil))) [1 2 3 4])"]
  ["map-indexed xform"  "[[0 :a] [1 :b]]" "(into [] (map-indexed vector) [:a :b])"]
  ["mapcat xform"       "[1 1 2 2]" "(into [] (mapcat (fn [x] [x x])) [1 2])"]
  ["cat xform"          "[1 2 3 4]" "(into [] cat [[1 2] [3 4]])"]
  ["into a set"         "#{2 3 4}"  "(into #{} (map inc) [1 2 3])"])

# transducer comp applies left-to-right: (comp (map a) (filter b)) maps then filters
(defspec "transducers / compose"
  ["comp map+filter"    "[2 4 6 8]" "(into [] (comp (map (fn [x] (* x 2))) (filter even?)) [1 2 3 4])"]
  ["comp filter+map"    "[2 4]"     "(into [] (comp (filter odd?) (map inc)) [1 2 3 4])"]
  ["comp three"         "[2]"       "(into [] (comp (map inc) (filter even?) (take 1)) [1 2 3 4])"])

(defspec "transducers / transduce & sequence"
  ["transduce sum"      "9"        "(transduce (map inc) + [1 2 3])"]
  ["transduce init"     "19"        "(transduce (map inc) + 10 [1 2 3])"]
  ["transduce filter"   "6"         "(transduce (filter even?) + [1 2 3 4])"]
  ["sequence xform"     "[2 3 4]"   "(sequence (map inc) [1 2 3])"]
  ["eduction"           "[2 3 4]"   "(into [] (eduction (map inc) [1 2 3]))"]
  ["completing"         "9"        "(transduce (map inc) (completing +) 0 [1 2 3])"])