Depends on which pier you dock at. Carnival seems to dock at two different piers. At Punta Lungasta (Spelling?) there is a hard rock store right there at the end of the pier. The resturant is further down the street, but still doable on a walk. The TAXIs are not that expensive, but I would ask someone at the the pier where it is at if you don't see it from the pier. That way you can judge if you want to walk or not. The taxi driver would be more than happy to drive you a couple of blocks and charge you $5...
Carnival Cruise Lines:
Fantasy 90, Celebration 95, Victory 05, Conquest 05, Spirit 6/06, Freedom 6/08, Holiday 7/08, Victory 6/09, Valor 9/09, Dream 6/10, Splendor 8/10,Conquest 8/11,Magic 11/11,Triumph 4/12,Spirit 7/12,Freedom 11/12, Triumph 2/13 - The fire cruise
NCL Dream October 2006, RCCL Mariner OTS June 2007, Celebrity Silhouette 2013