diff options
| -rw-r--r-- | StackSet.hs | 13 |
1 files changed, 8 insertions, 5 deletions
diff --git a/StackSet.hs b/StackSet.hs index 05a5ca3..e6af069 100644 --- a/StackSet.hs +++ b/StackSet.hs @@ -273,19 +273,22 @@ index = with [] integrate focusUp, focusDown, swapUp, swapDown :: StackSet i a s -> StackSet i a s focusUp = modify Empty focusUp' -focusUp' (Node t (l:ls) rs) = Node l ls (t:rs) -focusUp' (Node t [] rs) = Node x xs [] where (x:xs) = reverse (t:rs) - focusDown = modify Empty (reverseStack . focusUp' . reverseStack) swapUp = modify Empty swapUp' +swapDown = modify Empty (reverseStack . swapUp' . reverseStack) + +focusUp', swapUp' :: Stack a -> Stack a + +focusUp' (Node t (l:ls) rs) = Node l ls (t:rs) +focusUp' (Node t [] rs) = Node x xs [] where (x:xs) = reverse (t:rs) + swapUp' (Node t (l:ls) rs) = Node t ls (l:rs) swapUp' (Node t [] rs) = Node t (reverse rs) [] -swapDown = modify Empty (reverseStack . swapUp' . reverseStack) - -- reverse a stack: up becomes down and down becomes up. +reverseStack :: Stack a -> Stack a reverseStack (Node t ls rs) = Node t rs ls reverseStack x = x |