StackOverflow2013

Note that there are some explanatory texts on larger screens.

plurals

PO
primarykey
Id
8554777
data
AcceptedAnswerId
0
AnswerCount
0
ClosedDate
CommentCount
0
CommunityOwnedDate
CreationDate
2011-12-18T21:01:17.667
FavoriteCount
0
LastActivityDate
2011-12-18T21:38:02.127
LastEditDate
2011-12-18T21:38:02.127
LastEditorUserId
1097181
OwnerUserId
1097181
ParentId
8554756
PostTypeId
2
Score
4
ViewCount
0
LastEditorDisplayName
text
Body
You can simply do <code>Map.foldl' (+) 0</code> (or <code>M.foldl'</code>, if you imported Data.Map as <code>M</code>). This is just like <code>foldl' (+) 0 . Map.elems</code>, but slightly more efficient. (Don't forget the apostrophe — using foldl or foldr to do sums with the standard numeric types (Int, Integer, Float, Double, etc.) will build up huge thunks, which will use up lots of memory and possibly cause your program to overflow the stack.) However, only sufficiently recent versions of <a href="http://hackage.haskell.org/package/containers" rel="nofollow">containers</a> (>= 0.4.2.0) contain <a href="http://hackage.haskell.org/packages/archive/containers/0.4.2.0/doc/html/Data-Map.html#v%3afoldl-39-" rel="nofollow">Data.Map.foldl'</a>, and you shouldn't upgrade it with <code>cabal install</code>, since it comes with GHC. So unless you're on GHC 7.2 or above, <code>foldl' (+) 0 . Map.elems</code> is the best way to accomplish this. You could also use <a href="http://hackage.haskell.org/packages/archive/base/latest/doc/html/Data-Foldable.html#v%3asum" rel="nofollow">Data.Foldable.sum</a>, which works on any instance of the <a href="http://hackage.haskell.org/packages/archive/base/latest/doc/html/Data-Foldable.html#t%3aFoldable" rel="nofollow">Foldable</a> typeclass, but will still build up large thunks on the common numeric types. Here's a complete example: <pre><code>normalize :: (Fractional a) => Map k a -> Map k a normalize m = Map.map (/ total) m where total = foldl' (+) 0 $ Map.elems m </code></pre> You'll need to import Data.List to use <code>foldl'</code>.
Tags
Title
singulars
PostAcceptedAnswerId
1. This table or related slice is empty.
PostParentId
1. POSum over Haskell Map
 singulars
 PostTypePostTypeId
 PTQuestion
PostTypePostTypeId
1. PTAnswer
UserLastEditorUserId
1. USehird
UserOwnerUserId
1. USehird
plurals
PostLinksPostIdRelatedPostId
1. This table or related slice is empty.
PostLinksRelatedPostIdPostId
1. This table or related slice is empty.
PostsAcceptedAnswerId
1. POSum over Haskell Map
 singulars
 PostTypePostTypeId
 PTQuestion
PostsParentIdCreationDate
1. This table or related slice is empty.
VotesPostIdCreationDate
1. VO
 singulars
 PostPostId
 PO
 UserUserId
 This table or related slice is empty.
 VoteTypeVoteTypeId
 VTUpMod
2. VO
 singulars
 PostPostId
 PO
 UserUserId
 This table or related slice is empty.
 VoteTypeVoteTypeId
 VTUpMod
3. VO
 singulars
 PostPostId
 PO
 UserUserId
 This table or related slice is empty.
 VoteTypeVoteTypeId
 VTUpMod
CommentsPostId
1. This table or related slice is empty.

Querying!

Guidance

A row detail

Detail views are divided into sections. All the information in the data section comes from columns in the selected row. The other sections display data from other, related rows.

Related data can be related in a to-one or a to-many fashion. Captions of data related in a to-many fashion link to a list view showing a filtered view of the table.

Try moving around until you find a non-empty to-many entry and click on the label to get to one. You can move back to the root by clicking on the database name in the header.