73 lines
1.7 KiB
AppleScript
73 lines
1.7 KiB
AppleScript
-- KNUTH SHUFFLE -------------------------------------------------------------
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-- knuthShuffle :: [a] -> [a]
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on knuthShuffle(xs)
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-- randomSwap :: [Int] -> Int -> [Int]
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script randomSwap
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on |λ|(a, i)
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if i > 1 then
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set iRand to random number from 1 to i
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tell a
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set tmp to item iRand
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set item iRand to item i
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set item i to tmp
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it
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end tell
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else
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a
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end if
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end |λ|
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end script
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foldr(randomSwap, xs, enumFromTo(1, length of xs))
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end knuthShuffle
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-- TEST ----------------------------------------------------------------------
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on run
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knuthShuffle(["alpha", "beta", "gamma", "delta", "epsilon", ¬
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"zeta", "eta", "theta", "iota", "kappa", "lambda", "mu"])
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end run
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-- GENERIC FUNCTIONS ---------------------------------------------------------
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-- enumFromTo :: Int -> Int -> [Int]
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on enumFromTo(m, n)
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if m > n then
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set d to -1
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else
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set d to 1
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end if
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set lst to {}
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repeat with i from m to n by d
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set end of lst to i
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end repeat
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return lst
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end enumFromTo
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-- foldr :: (a -> b -> a) -> a -> [b] -> a
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on foldr(f, startValue, xs)
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tell mReturn(f)
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set v to startValue
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set lng to length of xs
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repeat with i from lng to 1 by -1
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set v to |λ|(v, item i of xs, i, xs)
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end repeat
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return v
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end tell
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end foldr
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-- Lift 2nd class handler function into 1st class script wrapper
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-- mReturn :: Handler -> Script
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on mReturn(f)
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if class of f is script then
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f
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else
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script
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property |λ| : f
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end script
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end if
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end mReturn
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