June 2018 Update

Task/Loop-over-multiple-arrays-simultaneously/AppleScript/loop-over-multiple-arrays-simultaneously-2.applescript

@@ -0,0 +1,75 @@
+-- CONCAT MAPPED OVER A TRANSPOSITION ----------------------------------------
+on run
+
+    unlines(map(concat, transpose([["a", "b", "c"], ["A", "B", "C"], [1, 2, 3]])))
+
+end run
+
+-- GENERIC FUNCTIONS ---------------------------------------------------------
+
+-- concat :: [[a]] -> [a] | [String] -> String
+on concat(xs)
+    if length of xs > 0 and class of (item 1 of xs) is string then
+        set acc to ""
+    else
+        set acc to {}
+    end if
+    repeat with i from 1 to length of xs
+        set acc to acc & item i of xs
+    end repeat
+    acc
+end concat
+
+-- intercalate :: String -> [String] -> String
+on intercalate(s, xs)
+    set {dlm, my text item delimiters} to {my text item delimiters, s}
+    set str to xs as text
+    set my text item delimiters to dlm
+    return str
+end intercalate
+
+-- 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
+
+-- transpose :: [[a]] -> [[a]]
+on transpose(xss)
+    script column
+        on |λ|(_, iCol)
+            script row
+                on |λ|(xs)
+                    item iCol of xs
+                end |λ|
+            end script
+
+            map(row, xss)
+        end |λ|
+    end script
+
+    map(column, item 1 of xss)
+end transpose
+
+-- unlines :: [String] -> String
+on unlines(xs)
+    intercalate(linefeed, xs)
+end unlines