diff options
| -rw-r--r-- | StackSet.hs | 8 |
1 files changed, 4 insertions, 4 deletions
diff --git a/StackSet.hs b/StackSet.hs index 037b124..265359c 100644 --- a/StackSet.hs +++ b/StackSet.hs @@ -487,7 +487,7 @@ swapMaster = modify' $ \c -> case c of -- element on the current stack, the original stackSet is returned. -- shift :: (Ord a, Eq s, Integral i) => i -> StackSet i a s sd -> StackSet i a s sd -shift n s = if and [n >= 0,n `tagMember` s, n /= tag (workspace (current s))] - then maybe s go (peek s) else s - where go w = foldr ($) s [view (tag (workspace (current s))),insertUp w,view n,delete w] - -- ^^ poor man's state monad :-) +shift n s = if n >= 0 && n `tagMember` s && n /= curtag + then maybe s go (peek s) else s + where go w = view curtag . insertUp w . view n . delete w $ s + curtag = tag (workspace (current s)) |