154 lines
3.2 KiB
AppleScript
154 lines
3.2 KiB
AppleScript
------------ ANONYMOUS RECURSION WITH THE Y-COMBINATOR --------
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on run
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--------------------- FIBONACCI EXAMPLE -------------------
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script
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on |λ|(f)
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script
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on |λ|(n)
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if 0 > n then return missing value
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if 0 = n then return 0
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if 1 = n then return 1
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(f's |λ|(n - 2)) + (f's |λ|(n - 1))
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end |λ|
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end script
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end |λ|
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end script
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unlines(map(showList, chunksOf(12, ¬
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map(|Y|(result), enumFromTo(-2, 20)))))
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end run
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------------------------ Y COMBINATOR ----------------------
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on |Y|(f)
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script
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on |λ|(y)
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script
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on |λ|(x)
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y's |λ|(y)'s |λ|(x)
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end |λ|
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end script
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f's |λ|(result)
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end |λ|
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end script
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result's |λ|(result)
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end |Y|
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----------- GENERIC FUNCTIONS FOR TEST AND DISPLAY ---------
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-- chunksOf :: Int -> [a] -> [[a]]
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on chunksOf(k, xs)
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script
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on go(ys)
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set ab to splitAt(k, ys)
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set a to item 1 of ab
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if {} ≠ a then
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{a} & go(item 2 of ab)
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else
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a
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end if
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end go
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end script
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result's go(xs)
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end chunksOf
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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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-- intercalate :: String -> [String] -> String
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on intercalate(delim, xs)
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set {dlm, my text item delimiters} to ¬
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{my text item delimiters, delim}
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set s to xs as text
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set my text item delimiters to dlm
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s
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end intercalate
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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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-- showList :: [a] -> String
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on showList(xs)
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intercalate(", ", map(my str, xs))
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end showList
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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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if class of xs is text then
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{items 1 thru n of xs as text, ¬
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items (n + 1) thru -1 of xs as text}
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else
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{items 1 thru n of xs, items (n + 1) thru -1 of xs}
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end if
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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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-- str :: a -> String
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on str(x)
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x as string
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end str
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-- unlines :: [String] -> String
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on unlines(xs)
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-- A single string formed by the intercalation
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-- of a list of strings with the newline character.
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set {dlm, my text item delimiters} to ¬
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{my text item delimiters, linefeed}
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set s to xs as text
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set my text item delimiters to dlm
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s
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end unlines
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