68 lines
1.1 KiB
AppleScript
68 lines
1.1 KiB
AppleScript
-- Compose (right to left) a list of ordinary 2nd class handlers (of arbitrary length)
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-- compose :: [(a -> a)] -> (a -> a)
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on compose(fs)
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script
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on lambda(x)
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script
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on lambda(a, f)
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mReturn(f)'s lambda(a)
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end lambda
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end script
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foldr(result, x, fs)
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end lambda
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end script
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end compose
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-- TEST
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on root(x)
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x ^ 0.5
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end root
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on succ(x)
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x + 1
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end succ
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on half(x)
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x / 2
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end half
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on run
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tell compose([half, succ, root]) to lambda(5)
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--> 1.61803398875
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end run
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-- GENERIC FUNCTIONS
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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 lambda(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 lambda : f
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end script
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end if
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end mReturn
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