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Finished koans 12

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Matt Davidson 2022-11-05 10:20:47 +00:00
parent 3e761f927a
commit 2bd286b9aa
1 changed files with 8 additions and 14 deletions
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22
src/koans/12_sequence_comprehensions.clj
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@ -3,34 +3,28 @@
(meditations (meditations
"Sequence comprehensions can bind each element in turn to a symbol" "Sequence comprehensions can bind each element in turn to a symbol"
(= __ (= '(0 1 2 3 4 5)
(for [x (range 6)] (for [x (range 6)] x))
x))
"They can easily emulate mapping" "They can easily emulate mapping"
(= '(0 1 4 9 16 25) (= '(0 1 4 9 16 25)
(map (fn [x] (* x x)) (map (fn [x] (* x x)) (range 6))
(range 6)) (for [x (range 6)] (* x x)))
(for [x (range 6)]
__))
"And also filtering" "And also filtering"
(= '(1 3 5 7 9) (= '(1 3 5 7 9)
(filter odd? (range 10)) (filter odd? (range 10))
(for [x __ :when (odd? x)] (for [x (range 10) :when (odd? x)]
x)) x))
"Combinations of these transformations are trivial" "Combinations of these transformations are trivial"
(= '(1 9 25 49 81) (= '(1 9 25 49 81)
(map (fn [x] (* x x)) (map (fn [x] (* x x)) (filter odd? (range 10)))
(filter odd? (range 10))) (for [x (range 10) :when (odd? x)] (* x x)))
(for [x (range 10) :when __]
__))
"More complex transformations simply take multiple binding forms" "More complex transformations simply take multiple binding forms"
(= [[:top :left] [:top :middle] [:top :right] (= [[:top :left] [:top :middle] [:top :right]
[:middle :left] [:middle :middle] [:middle :right] [:middle :left] [:middle :middle] [:middle :right]
[:bottom :left] [:bottom :middle] [:bottom :right]] [:bottom :left] [:bottom :middle] [:bottom :right]]
(for [row [:top :middle :bottom] (for [row [:top :middle :bottom]
column [:left :middle :right]] column [:left :middle :right]] [row column])))
__)))