INGI1131 - APE 2 - q10 optimisée

src/q6/oz-INGI1131/exercises/APE2/q10.oz

 declare
-fun {Flatten List}
-  case List
-  of nil then nil
-  [] H|T then {Append {Flatten H} {Flatten T}}
-  else [List]    
-  end
+fun {Flatten X}
+   fun {DoFlatten Xs Start End}
+      case Xs 
+      of X|Xr then S S1 in
+         if {DoFlatten X S S1} then 
+            S = Start 
+            {DoFlatten Xr S1 End}
+         else S2 in 
+            Start = X|S2 
+            {DoFlatten Xr S2 End}
+         end
+      [] nil then
+         Start = End 
+         true
+      else false
+      end
+   end
+   Start
+in
+   if {DoFlatten X Start nil} then Start 
+   else X 
+   end
 end
-
 {Browse {Flatten [a [b [c d]] e [[[f]]]]}} % -> [a b c d e f]
\ No newline at end of file