Solve sequence comprehensions

This commit is contained in:
Kenneth Kostresevic 2021-12-16 14:08:59 +01:00
parent a9c22921a5
commit c1f179948c

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@ -3,7 +3,7 @@
(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))
@ -12,20 +12,20 @@
(map (fn [x] (* x x)) (map (fn [x] (* x x))
(range 6)) (range 6))
(for [x (range 6)] (for [x (range 6)]
__)) (* x x)))
"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 is trivial" "Combinations of these transformations is 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 __] (for [x (range 10) :when (odd? x)]
__)) (* x x)))
"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]
@ -33,4 +33,4 @@
[: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]]
__))) (list row column))))