September Morn Update

Task/Apply-a-callback-to-an-array/AppleScript/apply-a-callback-to-an-array-2.applescript

@@ -3,8 +3,8 @@ on run
     set xs to {1, 2, 3, 4, 5, 6, 7, 8, 9, 10}
 
     {map(square, xs), ¬
-        filter(isEven, xs), ¬
-        foldl(sum, 0, xs)}
+        filter(even, xs), ¬
+        foldl(add, 0, xs)}
 
     --> {{1, 4, 9, 16, 25, 36, 49, 64, 81, 100}, {2, 4, 6, 8, 10}, 55}
 
@@ -15,43 +15,19 @@ on square(x)
     x * x
 end square
 
--- sum :: Num -> Num -> Num
-on sum(a, b)
+-- add :: Num -> Num -> Num
+on add(a, b)
     a + b
-end sum
+end add
 
--- isEven :: Int -> Bool
-on isEven(n)
-    n mod 2 = 0
-end isEven
+-- even :: Int -> Bool
+on even(x)
+    0 = x mod 2
+end even
 
 
 -- GENERIC HIGHER ORDER FUNCTIONS
 
--- 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 lambda(item i of xs, i, xs)
-        end repeat
-        return lst
-    end tell
-end map
-
--- 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 lambda(v, item i of xs, i, xs)
-        end repeat
-        return v
-    end tell
-end foldl
-
 -- filter :: (a -> Bool) -> [a] -> [a]
 on filter(f, xs)
     tell mReturn(f)
@@ -59,20 +35,44 @@ on filter(f, xs)
         set lng to length of xs
         repeat with i from 1 to lng
             set v to item i of xs
-            if lambda(v, i, xs) then set end of lst to v
+            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
+
 -- Lift 2nd class handler function into 1st class script wrapper
--- mReturn :: Handler -> Script
+-- mReturn :: First-class m => (a -> b) -> m (a -> b)
 on mReturn(f)
     if class of f is script then
         f
     else
         script
-            property lambda : f
+            property |λ| : f
         end script
     end if
 end mReturn
+
+-- 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