March 2014 update

Task/Flatten-a-list/JavaScript/flatten-a-list-1.js

@@ -0,0 +1,5 @@
+function flatten(list) {
+  return list.reduce(function (acc, val) {
+    return acc.concat(val.constructor === Array ? flatten(val) : val);
+  }, []);
+}

Task/Flatten-a-list/JavaScript/flatten-a-list-2.js

@@ -0,0 +1,5 @@
+let flatten = list => {
+  return list.reduce(
+    (a, b) => a.concat(Array.isArray(b) ? flatten(b) : b), []
+  );
+}

Task/Flatten-a-list/JavaScript/flatten-a-list.js

@@ -1,5 +0,0 @@
-function flatten(arr){
-    return arr.reduce(function(acc, val){
-        return acc.concat(val.constructor === Array ? flatten(val) : val);
-    },[]);
-}

Task/Flatten-a-list/Maple/flatten-a-list-1.maple

@@ -0,0 +1,5 @@
+L := [[1], 2, [[3,4], 5], [[[]]], [[[6]]], 7, 8, []]:
+
+with(ListTools):
+
+Flatten(L);

Task/Flatten-a-list/Maple/flatten-a-list-2.maple

@@ -0,0 +1,7 @@
+flatten := proc(x)
+  `if`(type(x,'list'),seq(procname(i),i = x),x);
+end proc:
+
+L := [[1], 2, [[3,4], 5], [[[]]], [[[6]]], 7, 8, []]:
+
+[flatten(L)];

Task/Flatten-a-list/Objective-C/flatten-a-list.m

@@ -0,0 +1,40 @@
+#import <Foundation/Foundation.h>
+
+@interface NSArray (FlattenExt)
+@property (nonatomic, readonly) NSArray *flattened;
+@end
+
+@implementation NSArray (FlattenExt)
+-(NSArray *) flattened {
+    NSMutableArray *flattened = [[NSMutableArray alloc] initWithCapacity:self.count];
+
+    for (id object in self) {
+        if ([object isKindOfClass:[NSArray class]])
+            [flattened addObjectsFromArray:((NSArray *)object).flattened];
+        else
+            [flattened addObject:object];
+    }
+
+    return [flattened autorelease];
+}
+@end
+
+int main() {
+    @autoreleasepool {
+        NSArray *p = @[
+		         @[ @1 ],
+		         @2,
+		         @[ @[@3, @4], @5],
+		         @[ @[ @[ ] ] ],
+		         @[ @[ @[ @6 ] ] ],
+		         @7,
+		         @8,
+		         @[ ] ];
+
+        for (id object in unflattened.flattened)
+            NSLog(@"%@", object);
+
+    }
+
+    return 0;
+}

Task/Flatten-a-list/PL-I/flatten-a-list.pli

@@ -1,6 +1,8 @@
 list = translate (list, '  ', '[]' );
 list = '[' || list || ']';
 
+
+
 /* the above will erroneously return:
 
 [  1 , 2,   3,4 , 5 ,       ,    6   , 7, 8,    ]

Task/Flatten-a-list/REXX/flatten-a-list-1.rexx

@@ -1,6 +1,6 @@
-/*REXX program  demonstrates  how to   flatten   a list.                */
+/*REXX pgm demonstrates how to flatten a list  (it need not be numeric).*/
 y = '[[1], 2, [[3,4], 5], [[[]]], [[[6]]], 7, 8, []]'
-z = '['changestr(' ', space( translate(y, , '[,]')), ", ")']'
+z = '['changestr(" ", space( translate(y, , '[,]')), ", ")']'
 say ' input =' y
 say 'output =' z
                                        /*stick a fork in it, we're done.*/

Task/Flatten-a-list/REXX/flatten-a-list-2.rexx

@@ -1,11 +1,12 @@
-/*REXX program  demonstrates  how to   flatten   a list.                */
+/*REXX pgm demonstrates how to flatten a list  (it need not be numeric).*/
 y = '[[1], 2, [[3,4], 5], [[[]]], [[[6]]], 7, 8, []]'
 
 z = translate( y, ,'[,]' )             /*change brackets&commas──►blanks*/
 z = space(z)                           /*remove extraneous blanks.      */
 z = changestr( ' ', z, ", " )          /*change blanks to "comma blank".*/
 z = '[' || z || "]"                    /*add brackets via concatenation.*/
-
+                                       /*another version of above:      */
+                                         z = '['z"]"
 say ' input =' y
 say 'output =' z
                                        /*stick a fork in it, we're done.*/