98 lines
2.1 KiB
AppleScript
98 lines
2.1 KiB
AppleScript
-- 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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-- TEST -----------------------------------------------------------------------
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on run
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-- Factorial
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script fact
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on |λ|(f)
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script
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on |λ|(n)
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if n = 0 then return 1
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n * (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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-- Fibonacci
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script fib
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on |λ|(f)
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script
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on |λ|(n)
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if n = 0 then return 0
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if n = 1 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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{facts:map(|Y|(fact), enumFromTo(0, 11)), fibs:map(|Y|(fib), enumFromTo(0, 20))}
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--> {facts:{1, 1, 2, 6, 24, 120, 720, 5040, 40320, 362880, 3628800, 39916800},
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--> fibs:{0, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, 144, 233, 377, 610, 987,
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-- 1597, 2584, 4181, 6765}}
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end run
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-- GENERIC FUNCTIONS FOR TEST -------------------------------------------------
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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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-- 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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-- 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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