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Description |
Assume you have a type like:
data Entry = Entry Author [Author] Updated Id Content
newtype Updated = Updated EpochTime
newtype Id = Id Int64
newtype Content = Content String
newtype Author = Author Email
type Email = String 1. Decide what parts of your type you want indexed, and
make your type an instance of Indexable
instance Indexable Entry () where
empty = IxSet[
,Ix (Map.empty::Map Author (Set Entry)) --out of order
,Ix (Map.empty::Map Id (Set Entry))
,Ix (Map.empty::Map Updated (Set Entry))
,Ix (Map.empty::Map Test (Set Entry)) -- bogus index
,Ix (Map.empty::Map Word (Set Entry)) -- text index
]
calcs entry = () -- words for text indexing purposes 3. Use insert,delete,replace and empty to build up an IxSet collection
entries = foldr insert empty [e1,e2,e3,e4]
entries' = foldr delete entries [e1,e3]
entries'' = update e4 e5 entries
4. Use the query functions below to grab data from it. e.g.
entries @< (Updated t1) @= (Author "john@doe.com") will find all items in entries updated earlier than t1 by
john@doe.com.
5. Text Index
If you want to do add a text index extract the words in entry and pass
them in the calc method of the Indexable class. Then if you want
all entries with either word1 or word2, you change the instance to
getWords entry = let Just (Content s) =
gGet entry in map Word $ words s instance Indexable Entry [Word] where
....
calcs entry = getWords entry Now you can do this query to find entries with any of the words
entries @+ [Word "word1",Word "word2"] And if you want all entries with both:
entries @* [Word "word1",Word "word2"] 6. Find the only the first author
If an Entry has multiple authors and you want to be able to query
on the first author, define a FirstAuthor datatype and add it to the
result of calc. calc e=(toWords e,getFirstAuthor e) and now you can
do
newtype FirstAuthor = FirstAuthor Email
getFirstAuthor = let Just (Author a)=gGet Entry in FirstAuthor a
instance Indexable Entry ([Word],FirstAuthor)
...
empty = ....
Ix (Map.empty::Map FirstAuthor (Set Entry))]
calcs entry = (getWords Entry,getFirstAuthor entry)
entries @= (FirstAuthor "john@doe.com") -- guess what this does |
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Synopsis |
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| | iSetConstr :: Constr | | ixSetConstr :: Constr | | ixSetDataType :: DataType | | class Data b => Indexable a b | a -> b where | | | noCalcs :: t -> () | | inferIxSet :: String -> Name -> Name -> [Name] -> Q [Dec] | | flatten :: (Typeable a, Data a) => a -> [Dynamic] | | type IndexOp = forall k a. (Ord k, Ord a) => k -> a -> Map k (Set a) -> Map k (Set a) | | change :: (Data a, Ord a, Data b, Indexable a b) => IndexOp -> a -> IxSet a -> IxSet a | | insert :: (Data a, Ord a, Data b, Indexable a b) => a -> IxSet a -> IxSet a | | delete :: (Data a, Ord a, Data b, Indexable a b) => a -> IxSet a -> IxSet a | | updateIx :: (Indexable a b, Ord a, Data a, Typeable k) => k -> a -> IxSet a -> IxSet a | | toSet :: Ord a => IxSet a -> Set a | | toSet' :: Ord a => [Ix a] -> Set a | | fromSet :: (Indexable a b, Ord a, Data a) => Set a -> IxSet a | | fromSet' :: (Indexable a b, Ord a, Data a) => Set a -> IxSet a | | fromList :: (Indexable a b, Ord a, Data a) => [a] -> IxSet a | | size :: Ord a => IxSet a -> Int | | toList :: Ord a => IxSet a -> [a] | | toList' :: Ord a => [Ix a] -> [a] | | getOne :: Ord a => IxSet a -> Maybe a | | getOneOr :: Ord a => a -> IxSet a -> a | | (&&&) :: (Ord a, Data a, Indexable a b) => IxSet a -> IxSet a -> IxSet a | | (|||) :: (Ord a, Data a, Indexable a b) => IxSet a -> IxSet a -> IxSet a | | union :: (Ord a, Data a, Indexable a b) => IxSet a -> IxSet a -> IxSet a | | intersection :: (Ord a, Data a, Indexable a b) => IxSet a -> IxSet a -> IxSet a | | (@=) :: (Indexable a b, Data a, Ord a, Typeable k) => IxSet a -> k -> IxSet a | | (@<) :: (Indexable a b, Data a, Ord a, Typeable k) => IxSet a -> k -> IxSet a | | (@>) :: (Indexable a b, Data a, Ord a, Typeable k) => IxSet a -> k -> IxSet a | | (@<=) :: (Indexable a b, Data a, Ord a, Typeable k) => IxSet a -> k -> IxSet a | | (@>=) :: (Indexable a b, Data a, Ord a, Typeable k) => IxSet a -> k -> IxSet a | | (@><) :: (Indexable a b, Data a, Ord a, Typeable k) => IxSet a -> (k, k) -> IxSet a | | (@>=<) :: (Indexable a b, Data a, Ord a, Typeable k) => IxSet a -> (k, k) -> IxSet a | | (@><=) :: (Indexable a b, Data a, Ord a, Typeable k) => IxSet a -> (k, k) -> IxSet a | | (@>=<=) :: (Indexable a b, Data a, Ord a, Typeable k) => IxSet a -> (k, k) -> IxSet a | | (@+) :: (Indexable a b, Data a, Ord a, Typeable k) => IxSet a -> [k] -> IxSet a | | (@*) :: (Indexable a b, Data a, Ord a, Typeable k) => IxSet a -> [k] -> IxSet a | | getEQ :: (Indexable a b, Data a, Ord a, Typeable k) => k -> IxSet a -> IxSet a | | getLT :: (Indexable a b, Data a, Ord a, Typeable k) => k -> IxSet a -> IxSet a | | getGT :: (Indexable a b, Data a, Ord a, Typeable k) => k -> IxSet a -> IxSet a | | getLTE :: (Indexable a b, Data a, Ord a, Typeable k) => k -> IxSet a -> IxSet a | | getGTE :: (Indexable a b, Data a, Ord a, Typeable k) => k -> IxSet a -> IxSet a | | getRange :: (Indexable a b, Typeable k, Ord a, Data a) => k -> k -> IxSet a -> IxSet a | | groupBy :: (Typeable k, Typeable t) => IxSet t -> [(k, [t])] | | rGroupBy :: (Typeable k, Typeable t) => IxSet t -> [(k, [t])] | | getOrd :: (Indexable a b, Ord a, Data a, Typeable k) => Ordering -> k -> IxSet a -> IxSet a | | module Ix |
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Documentation |
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Constructors | | Instances | Typeable1 IxSet | (Data ctx a, Sat (ctx (IxSet a)), Sat (ctx ([] a)), Indexable a b, Data a, Ord a) => Data ctx (IxSet a) | Data a => Data (IxSet a) | (Ord a, Read a, Data a, Indexable a b) => Read (IxSet a) | (Ord a, Show a) => Show (IxSet a) | (Show a, Indexable a b, Data a, Ord a) => Monoid (IxSet a) | Version (IxSet a) | (Serialize a, Ord a, Data a, Indexable a b) => Serialize (IxSet a) | (Indexable a b, Data a, Ord a, Default a) => Default (IxSet a) |
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class Data b => Indexable a b | a -> b where | Source |
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empty defines what an empty IxSet for this particular type should look
like.
calcs adds indexable values not found in the type.
If you don't want calculated values use Indexable a ().
| | Methods | | | Instances | |
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Function to be used for calcs in the case of an Indexable a () instance
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Generically traverses the argument and converts all data in it to Dynamic
and returns all the iternal data as a list of Dynamic
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Higher order operator for modifying IxSets. Use this when your final
function should have the form a->IxSet a->IxSet a, e.g. insert.
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Inserts an item into the IxSet
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Removes an item from the IxSet
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Will replace the item with index k. Only works if there is at most one
item with that index in the IxSet.
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Converts an IxSet to a Set of its elements
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Takes a list of Ixs and converts it into a Set
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Converts a Set to an IxSet
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Converts a Set to an IxSet
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Converts a list to an IxSet
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Returns the number of unique items in the IxSet
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Converts an IxSet to its list of elements.
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Converts a list of Ix's
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If the IxSet is a singleton it will return the one item stored, else Nothing.
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getOne with a user provided default
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An infix intersection operation
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An infix union operation
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Takes the union of the two IxSets
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Takes the intersection of the two IxSets
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Infix version of getEQ
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Infix version of getLT
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Infix version of getGT
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Infix version of getLTE
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Infix version of getGTE
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Returns the subset with indices in the open interval (k,k)
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Returns the subset with indices in [k,k)
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Returns the subset with indices in (k,k]
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Returns the subset with indices in [k,k]
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Creates the subset that has an index in the provided list.
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Creates the subset that matches all the provided indices.
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Returns the subset with an index equal to the provided key.
It is possible to provide a key of a type not indexed in the IxSet. In
this case the function returns the empty IxSet for this type.
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Returns the subset with an index less than the provided key.
It is possible to provide a key of a type not indexed in the IxSet. In
this case the function returns the empty IxSet for this type.
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Returns the subset with an index greater than the provided key.
It is possible to provide a key of a type not indexed in the IxSet. In
this case the function returns the empty IxSet for this type.
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Returns the subset with an index less than or equal to the provided key.
It is possible to provide a key of a type not indexed in the IxSet. In
this case the function returns the empty IxSet for this type.
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Returns the subset with an index greater than or equal to the provided key.
It is possible to provide a key of a type not indexed in the IxSet. In
this case the function returns the empty IxSet for this type.
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Returns the subset with an index within the interval provided.
The top of the interval is closed and the bottom is open.
It is possible to provide a key of a type not indexed in the IxSet. In
this case the function returns the empty IxSet for this type.
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Returns lists of elements paired with the indices determined by type
inference.
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A reversed groupBy
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A function for building up selectors on IxSets. Used in the various get*
functions.
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module Ix |
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Produced by Haddock version 2.4.2 |