Initial data commit

Task/Perfect-numbers/AppleScript/perfect-numbers-1.applescript

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+-- PERFECT NUMBERS -----------------------------------------------------------
+
+-- perfect :: integer -> bool
+on perfect(n)
+
+    -- isFactor :: integer -> bool
+    script isFactor
+        on |λ|(x)
+            n mod x = 0
+        end |λ|
+    end script
+
+    -- quotient :: number -> number
+    script quotient
+        on |λ|(x)
+            n / x
+        end |λ|
+    end script
+
+    -- sum :: number -> number -> number
+    script sum
+        on |λ|(a, b)
+            a + b
+        end |λ|
+    end script
+
+    -- Integer factors of n below the square root
+    set lows to filter(isFactor, enumFromTo(1, (n ^ (1 / 2)) as integer))
+
+    -- low and high factors (quotients of low factors) tested for perfection
+    (n > 1) and (foldl(sum, 0, (lows & map(quotient, lows))) / 2 = n)
+end perfect
+
+
+-- TEST ----------------------------------------------------------------------
+on run
+
+    filter(perfect, enumFromTo(1, 10000))
+
+    --> {6, 28, 496, 8128}
+
+end run
+
+
+-- GENERIC FUNCTIONS ---------------------------------------------------------
+
+-- enumFromTo :: Int -> Int -> [Int]
+on enumFromTo(m, n)
+    if m > n then
+        set d to -1
+    else
+        set d to 1
+    end if
+    set lst to {}
+    repeat with i from m to n by d
+        set end of lst to i
+    end repeat
+    return lst
+end enumFromTo
+
+-- filter :: (a -> Bool) -> [a] -> [a]
+on filter(f, xs)
+    tell mReturn(f)
+        set lst to {}
+        set lng to length of xs
+        repeat with i from 1 to lng
+            set v to item i of xs
+            if |λ|(v, i, xs) then set end of lst to v
+        end repeat
+        return lst
+    end tell
+end filter
+
+-- foldl :: (a -> b -> a) -> a -> [b] -> a
+on foldl(f, startValue, xs)
+    tell mReturn(f)
+        set v to startValue
+        set lng to length of xs
+        repeat with i from 1 to lng
+            set v to |λ|(v, item i of xs, i, xs)
+        end repeat
+        return v
+    end tell
+end foldl
+
+-- map :: (a -> b) -> [a] -> [b]
+on map(f, xs)
+    tell mReturn(f)
+        set lng to length of xs
+        set lst to {}
+        repeat with i from 1 to lng
+            set end of lst to |λ|(item i of xs, i, xs)
+        end repeat
+        return lst
+    end tell
+end map
+
+-- Lift 2nd class handler function into 1st class script wrapper
+-- mReturn :: Handler -> Script
+on mReturn(f)
+    if class of f is script then
+        f
+    else
+        script
+            property |λ| : f
+        end script
+    end if
+end mReturn