159 lines
3.5 KiB
AppleScript
159 lines
3.5 KiB
AppleScript
-- zigzagMatrix
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on zigzagMatrix(n)
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-- diagonals :: n -> [[n]]
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script diagonals
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on |λ|(n)
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script mf
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on diags(xs, iCol, iRow)
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if (iCol < length of xs) then
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if iRow < n then
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set iNext to iCol + 1
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else
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set iNext to iCol - 1
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end if
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set {headList, tail} to splitAt(iCol, xs)
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{headList} & diags(tail, iNext, iRow + 1)
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else
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{xs}
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end if
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end diags
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end script
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diags(enumFromTo(0, n * n - 1), 1, 1) of mf
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end |λ|
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end script
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-- oddReversed :: [a] -> Int -> [a]
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script oddReversed
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on |λ|(lst, i)
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if i mod 2 = 0 then
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lst
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else
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reverse of lst
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end if
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end |λ|
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end script
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rowsFromDiagonals(n, map(oddReversed, |λ|(n) of diagonals))
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end zigzagMatrix
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-- Rows of given length from list of diagonals
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-- rowsFromDiagonals :: Int -> [[a]] -> [[a]]
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on rowsFromDiagonals(n, lst)
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if length of lst > 0 then
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-- lengthOverOne :: [a] -> Bool
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script lengthOverOne
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on |λ|(lst)
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length of lst > 1
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end |λ|
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end script
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set {edge, residue} to splitAt(n, lst)
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{map(my head, edge)} & ¬
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rowsFromDiagonals(n, ¬
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map(my tail, ¬
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filter(lengthOverOne, edge)) & residue)
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else
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{}
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end if
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end rowsFromDiagonals
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-- TEST -----------------------------------------------------------------------
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on run
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zigzagMatrix(5)
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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 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 enumFromTo
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-- filter :: (a -> Bool) -> [a] -> [a]
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on filter(f, xs)
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tell mReturn(f)
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set lst to {}
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set lng to length of xs
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repeat with i from 1 to lng
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set v to item i of xs
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if |λ|(v, i, xs) then set end of lst to v
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end repeat
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return lst
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end tell
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end filter
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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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-- 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 |λ|(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 |λ| : f
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end script
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end if
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end mReturn
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-- splitAt:: n -> list -> {n items from start of list, rest of list}
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-- splitAt :: Int -> [a] -> ([a], [a])
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on splitAt(n, xs)
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if n > 0 and n < length of xs then
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{items 1 thru n of xs, items (n + 1) thru -1 of xs}
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else
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if n < 1 then
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{{}, xs}
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else
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{xs, {}}
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end if
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end if
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end splitAt
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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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