--- a/Collection.st	Wed Feb 04 18:35:14 2015 +0100
+++ b/Collection.st	Wed Feb 04 20:35:49 2015 +0100
@@ -275,6 +275,7 @@
     ^ self newWithSize:n
 ! !
 
+
 !Collection class methodsFor:'Signal constants'!
 
 emptyCollectionSignal
@@ -532,6 +533,7 @@
     "Created: / 22-10-2008 / 21:29:27 / cg"
 ! !
 
+
 !Collection methodsFor:'accessing'!
 
 anElement
@@ -2451,6 +2453,27 @@
     "
 !
 
+collectWithIndex:aTwoArgBlock
+    "for each element in the receiver and a running index, 
+     evaluate the argument, aTwoArgBlock.
+     Return a new collection with the results"
+
+    |newCollection runIndex|
+
+    newCollection := self species new.
+    runIndex := 1.
+    self do:[:element | 
+        newCollection add:(aTwoArgBlock value:element value:runIndex).
+        runIndex := runIndex + 1.
+    ].
+    ^ newCollection
+
+    "
+     #(1 2 3 4) collectWithIndex:[:n :i | n * 2 + i]  
+     #(1 2 3 4) collectWithIndex:[:n :i | i -> (n * 2)]  
+    "
+!
+
 count:aBlock
     "count elements, for which aBlock returns true.
      Return the sum."
@@ -5665,11 +5688,11 @@
 !Collection class methodsFor:'documentation'!
 
 version
-    ^ '$Header: /cvs/stx/stx/libbasic/Collection.st,v 1.355 2015-02-03 14:21:50 cg Exp $'
+    ^ '$Header: /cvs/stx/stx/libbasic/Collection.st,v 1.356 2015-02-04 19:35:49 cg Exp $'
 !
 
 version_CVS
-    ^ '$Header: /cvs/stx/stx/libbasic/Collection.st,v 1.355 2015-02-03 14:21:50 cg Exp $'
+    ^ '$Header: /cvs/stx/stx/libbasic/Collection.st,v 1.356 2015-02-04 19:35:49 cg Exp $'
 ! !