Opaleye.Internal.Window

Documentation

newtype WindowFunction a b

WindowFunction represents expressions that contain window functions. You can choose a WindowFunction from the options below, and combine and manipulate them using the Applicative and Profunctor operations.

Constructors

WindowFunction (PackMap WndwOp PrimExpr a b)

Instances

Profunctor WindowFunction

Defined in Opaleye.Internal.Window

Methods

dimap :: (a -> b) -> (c -> d) -> WindowFunction b c -> WindowFunction a d

lmap :: (a -> b) -> WindowFunction b c -> WindowFunction a c

rmap :: (b -> c) -> WindowFunction a b -> WindowFunction a c

(#.) :: forall a b c q. Coercible c b => q b c -> WindowFunction a b -> WindowFunction a c

(.#) :: forall a b c q. Coercible b a => WindowFunction b c -> q a b -> WindowFunction a c

Applicative (WindowFunction a)

Defined in Opaleye.Internal.Window

Methods

pure :: a0 -> WindowFunction a a0

(<*>) :: WindowFunction a (a0 -> b) -> WindowFunction a a0 -> WindowFunction a b

liftA2 :: (a0 -> b -> c) -> WindowFunction a a0 -> WindowFunction a b -> WindowFunction a c

(*>) :: WindowFunction a a0 -> WindowFunction a b -> WindowFunction a b

(<*) :: WindowFunction a a0 -> WindowFunction a b -> WindowFunction a a0

Functor (WindowFunction a)

Defined in Opaleye.Internal.Window

Methods

fmap :: (a0 -> b) -> WindowFunction a a0 -> WindowFunction a b

(<$) :: a0 -> WindowFunction a b -> WindowFunction a a0

newtype Windows a b

You can create Windows using over, and combine and manipulate them using the Applicative and Profunctor operations.

Constructors

Windows (PackMap (WndwOp, Window a) PrimExpr a b)

Instances

Profunctor Windows

Defined in Opaleye.Internal.Window

Methods

dimap :: (a -> b) -> (c -> d) -> Windows b c -> Windows a d

lmap :: (a -> b) -> Windows b c -> Windows a c

rmap :: (b -> c) -> Windows a b -> Windows a c

(#.) :: forall a b c q. Coercible c b => q b c -> Windows a b -> Windows a c

(.#) :: forall a b c q. Coercible b a => Windows b c -> q a b -> Windows a c

Applicative (Windows a)

Defined in Opaleye.Internal.Window

Methods

pure :: a0 -> Windows a a0

(<*>) :: Windows a (a0 -> b) -> Windows a a0 -> Windows a b

liftA2 :: (a0 -> b -> c) -> Windows a a0 -> Windows a b -> Windows a c

(*>) :: Windows a a0 -> Windows a b -> Windows a b

(<*) :: Windows a a0 -> Windows a b -> Windows a a0

Functor (Windows a)

Defined in Opaleye.Internal.Window

Methods

fmap :: (a0 -> b) -> Windows a a0 -> Windows a b

(<$) :: a0 -> Windows a b -> Windows a a0

runWindows' :: Applicative f => Windows a b -> ((WndwOp, Window a) -> f PrimExpr) -> a -> f b

extractWindowFields :: Tag -> a -> (WndwOp, Window a) -> PM (Bindings (WndwOp, Partition)) PrimExpr

noWindowFunction :: (a -> b) -> WindowFunction a b

A WindowFunction that doesn't actually contain any window function.

runWindows :: Windows a b -> Select a -> Select b

runWindows runs a query composed of expressions containing window functions. runWindows is similar to aggregate, with the main difference being that in a window query, each input row corresponds to one output row, whereas aggregation queries fold the entire input query down into a single row per group. In Haskell terminology, aggregate is to foldl as runWindows is to scanl.

windowsApply :: Windows (Windows a b, a) b

makeWndw :: WindowFunction WndwOp (Field_ n a)

makeWndwField :: (PrimExpr -> WndwOp) -> WindowFunction (Field_ n a) (Field_ n' a')

makeWndwAny :: WndwOp -> WindowFunction a (Field_ n b)

aggregatorWindowFunction :: Aggregator a b -> (a' -> a) -> WindowFunction a' b

aggregatorWindowFunction allows the use of Aggregators in WindowFunctions. In particular, aggregatorWindowFunction sum gives a running total (when combined with an order argument to over).

over :: WindowFunction a b -> Window a -> Order a -> Windows a b

over applies a WindowFunction on a particular Window. For example,

over (aggregatorWindowFunction sum salary) (partitionBy department) (desc salary)

If you want to use a Window that consists of the entire SELECT then supply mempty for the Window a argument. If you don't want to order the Window then supply mempty for the Order a argument.

data Window a

In PostgreSQL, window functions must specify the "window" over which they operate. The syntax for this looks like: SUM(salary) OVER (PARTITION BY department). The Opaleye type Window represents the segment consisting of the PARTIION BY.

You can create a Window using partitionBy and combine two Windows in a single one which combines the partition of both by using <>.

Constructors

Window (a -> [PrimExpr]) (Order a)

Instances

Contravariant Window

Defined in Opaleye.Internal.Window

Methods

contramap :: (a' -> a) -> Window a -> Window a'

(>$) :: b -> Window b -> Window a

Monoid (Window a)

Defined in Opaleye.Internal.Window

Methods

mempty :: Window a

mappend :: Window a -> Window a -> Window a

mconcat :: [Window a] -> Window a

Semigroup (Window a)

Defined in Opaleye.Internal.Window

Methods

(<>) :: Window a -> Window a -> Window a

sconcat :: NonEmpty (Window a) -> Window a

stimes :: Integral b => b -> Window a -> Window a

partitionBy :: (a -> Field_ n b) -> Window a

The window where each partition shares the same value for the given Field.

orderPartitionBy :: Order a -> Window a

Controls the order in which rows are processed by window functions. This does not need to match the ordering of the overall query.