105 lines
1.8 KiB
AppleScript
105 lines
1.8 KiB
AppleScript
-- comb :: Int -> [a] -> [[a]]
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on comb(n, lst)
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set h to head(lst)
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script headPrepended
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on lambda(t)
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h & t
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end lambda
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end script
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if n < 1 then
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[[]]
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else if length of lst = 0 then
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[]
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else
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set xs to tail(lst)
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map(headPrepended, ¬
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comb(n - 1, xs)) & comb(n, xs)
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end if
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end comb
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-- TEST
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-- spaced :: [a] -> String
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on spaced(lst)
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intercalate(space, lst)
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end spaced
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on run
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intercalate(linefeed, ¬
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map(spaced, comb(3, range(0, 4))))
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end run
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-- GENERIC FUNCTIONS
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-- map :: (a -> b) -> [a] -> [b]
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on map(f, xs)
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tell mReturn(f)
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set lng to length of xs
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set lst to {}
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repeat with i from 1 to lng
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set end of lst to lambda(item i of xs, i, xs)
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end repeat
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return lst
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end tell
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end map
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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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-- intercalate :: Text -> [Text] -> Text
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on intercalate(strText, lstText)
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set {dlm, my text item delimiters} to {my text item delimiters, strText}
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set strJoined to lstText as text
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set my text item delimiters to dlm
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return strJoined
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end intercalate
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-- range :: Int -> Int -> [Int]
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on range(m, n)
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if n < m 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 range
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-- head :: [a] -> a
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on head(xs)
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if length of xs > 0 then
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item 1 of xs
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else
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missing value
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end if
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end head
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-- tail :: [a] -> [a]
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on tail(xs)
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if length of xs > 1 then
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items 2 thru -1 of xs
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else
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{}
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end if
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end tail
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