[Haskell-cafe] Pruning the tree

Now I have my infinite tree inf t =Leaf "1" treeGrower :: Tree String-> Tree String treeGrower (Leaf a )= treeGrower (Fork (Leaf (a++"1")) (Leaf (a++"2"))) treeGrower (Fork l r) = Fork (treeGrower l) (treeGrower r) data Tree a = Fork (Tree a) (Tree a) | Leaf a deriving Show inf=treeGrower t I'd like to prune it to a level to have a show of a piece like piece= prune 5 inf How prune is to be coded ?? Thanks Paolino