Is the call to "go" in the following code considered as tail recursion?

data DList a = DLNode (DList a) a (DList a)

 
mkDList :: [a] -> DList a
 
mkDList [] = error "must have at least one element"

mkDList xs = let (first,last) = go last xs first

             in  first
 
  where go :: DList a -> [a] -> DList a -> (DList a, DList a)

        go prev []     next = (next,prev)
        go prev (x:xs) next = let this        = DLNode prev x rest

                                  (rest,last) = go this xs next

                              in  (this,last)

Daryoush