Time for an 2014 update…

Task/Sorting-algorithms-Merge-sort/Groovy/sorting-algorithms-merge-sort-3.groovy

@@ -0,0 +1,19 @@
+split = { list ->
+    list.collate((list.size()+1)/2 as int)
+}
+
+merge = { left, right, headBuffer=[] ->
+    if(left.size() == 0) headBuffer+right
+    else if(right.size() == 0) headBuffer+left
+    else if(left.head() <= right.head()) merge.trampoline(left.tail(), right, headBuffer+left.head())
+    else merge.trampoline(right.tail(), left, headBuffer+right.head())
+}.trampoline()
+
+mergesort = { List list ->
+    if(list.size() < 2) list
+    else merge(split(list).collect {mergesort it})
+}
+
+assert mergesort((500..1)) == (1..500)
+assert mergesort([5,4,6,3,1,2]) == [1,2,3,4,5,6]
+assert mergesort([3,3,1,4,6,78,9,1,3,5]) == [1,1,3,3,3,4,5,6,9,78]

Task/Sorting-algorithms-Merge-sort/Groovy/sorting-algorithms-merge-sort-4.groovy

@@ -0,0 +1,4 @@
+split = { list, left=[], right=[] ->
+    if(list.size() <2) [list+left, right]
+    else split.trampoline(list.tail().tail(), [list.head()]+left,[list.tail().head()]+right)
+}.trampoline()