StackOverflow2013

Note that there are some explanatory texts on larger screens.

plurals

PO
primarykey
Id
18928482
data
AcceptedAnswerId
0
AnswerCount
0
ClosedDate
CommentCount
1
CommunityOwnedDate
CreationDate
2013-09-21T03:07:56.370
FavoriteCount
0
LastActivityDate
2013-09-21T03:22:26.433
LastEditDate
2013-09-21T03:22:26.433
LastEditorUserId
784338
OwnerUserId
784338
ParentId
18928176
PostTypeId
2
Score
9
ViewCount
0
LastEditorDisplayName
text
Body
Well um, I think you're a bit off. A monad is an endofunctor, which in Hask (The category of Haskell types) is something with the kind <code>F :: * -> *</code> with some function that knows how to inject morphisms (functions) into the subcategory of Hask with functions upon <code>F</code>s as morphisms and <code>F</code>s as objects, <code>fmap</code>. What you have there appears to be a natural transformation in Hask. Examples: <code>Maybe</code>, <code>Either a</code>, <code>(,) a</code>, etc.. Now a monad also must have 2 natural transformations (<code>Functor F, Functor g => F a -> G a</code> in hask). <pre><code>n : Identity -> M u : M^2 -> M </code></pre> Or in haskell code <pre><code>n :: Identity a -> M a -- Identity a == a u :: M (M a) -> M a </code></pre> which correspond to <code>return</code> and <code>join</code> respectively. Now we have to get to <code>>>=</code>. What you had as bind was actually just <code>fmap</code>, what we actually want is <code>m a -> (a -> m b) -> m b</code>. This is easily defined as <pre><code> m >>= f = join $ f `fmap` m </code></pre> Tada! We have monads. Now for this monoid of endofunctors. A monoid over endofunctors would have a functors as objects and natural transformations as morphisms. The interesting thing is that the product of two endofunctors is their composition. Here's the Haskell code for our new monoid <pre><code>type (f <+> g) a = f (g a) class Functor m => Monoid' m where midentity' :: Identity a -> m a mappend' :: (m <+> m) a -> m a </code></pre> This desugars to <pre><code> midentity' :: a -> m a mappend' :: m (m a) -> m a </code></pre> Look familiar?
Tags
Title
singulars
PostAcceptedAnswerId
1. This table or related slice is empty.
PostParentId
1. POMonads from all angles - Mathematical, diagramatic and programmatical
 singulars
 PostTypePostTypeId
 PTQuestion
PostTypePostTypeId
1. PTAnswer
UserLastEditorUserId
1. USjozefg
UserOwnerUserId
1. USjozefg
plurals
PostLinksPostIdRelatedPostId
1. This table or related slice is empty.
PostLinksRelatedPostIdPostId
1. This table or related slice is empty.
PostsAcceptedAnswerId
1. POMonads from all angles - Mathematical, diagramatic and programmatical
 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. COaah, Monad is endofuctor, how did I miss that. It's now clear, thanks.
 singulars
 PostPostId
 PO
 UserUserId
 USDev Maha

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.