d919181 · rel8 · git.iko.soy

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Document Rel8.Expr.Order

d919181Ollie Charles6 years ago

src/Rel8/Expr/Order.hs+18

compare with master

unifiedsplit

@@ -27,6 +27,10 @@ import Rel8.Order ( Order( Order ) )

27import Rel8.Type.Ord ( DBOrd )

30+-- | Sort a column in ascending order.

31+--

32+-- >>> select c $ orderBy asc $ values [ lit x | x <- [1..5 :: Int32] ]

33+-- [1,2,3,4,5]

30asc :: DBOrd a => Order (Expr a)

34asc :: DBOrd a => Order (Expr a)

31asc = Order $ Opaleye.Order (\expr -> [(orderOp, toPrimExpr expr)])

35asc = Order $ Opaleye.Order (\expr -> [(orderOp, toPrimExpr expr)])

32 where

36 where

@@ -37,6 +41,10 @@ asc = Order $ Opaleye.Order (\expr -> [(orderOp, toPrimExpr expr)])

37 }

41 }

44+-- | Sort a column in descending order.

45+--

46+-- >>> select c $ orderBy desc $ values [ lit x | x <- [1..5 :: Int32] ]

47+-- [5,4,3,2,1]

40desc :: DBOrd a => Order (Expr a)

48desc :: DBOrd a => Order (Expr a)

41desc = Order $ Opaleye.Order (\expr -> [(orderOp, toPrimExpr expr)])

49desc = Order $ Opaleye.Order (\expr -> [(orderOp, toPrimExpr expr)])

42 where

50 where

@@ -47,6 +55,11 @@ desc = Order $ Opaleye.Order (\expr -> [(orderOp, toPrimExpr expr)])

47 }

55 }

58+-- | Transform an ordering so that @null@ values appear first. This corresponds

59+-- to @NULLS FIRST@ in SQL.

60+--

61+-- >>> select c $ orderBy (nullsFirst desc) $ values $ [ nullExpr, nullExpr ] <> [ lit (Just x) | x <- [1..5 :: Int32] ]

62+-- [Nothing,Nothing,Just 5,Just 4,Just 3,Just 2,Just 1]

50nullsFirst :: Order (Expr a) -> Order (Expr (Maybe a))

63nullsFirst :: Order (Expr a) -> Order (Expr (Maybe a))

51nullsFirst (Order (Opaleye.Order f)) =

64nullsFirst (Order (Opaleye.Order f)) =

52 Order $ Opaleye.Order $ fmap (first g) . f . unsafeUnnullify

65 Order $ Opaleye.Order $ fmap (first g) . f . unsafeUnnullify

@@ -55,6 +68,11 @@ nullsFirst (Order (Opaleye.Order f)) =

55 g orderOp = orderOp { Opaleye.orderNulls = Opaleye.NullsFirst }

68 g orderOp = orderOp { Opaleye.orderNulls = Opaleye.NullsFirst }

71+-- | Transform an ordering so that @null@ values appear first. This corresponds

72+-- to @NULLS LAST@ in SQL.

73+--

74+-- >>> select c $ orderBy (nullsLast desc) $ values $ [ nullExpr, nullExpr ] <> [ lit (Just x) | x <- [1..5 :: Int32] ]

75+-- [Just 5,Just 4,Just 3,Just 2,Just 1,Nothing,Nothing]

58nullsLast :: Order (Expr a) -> Order (Expr (Maybe a))

76nullsLast :: Order (Expr a) -> Order (Expr (Maybe a))

59nullsLast (Order (Opaleye.Order f)) =

77nullsLast (Order (Opaleye.Order f)) =

60 Order $ Opaleye.Order $ fmap (first g) . f . unsafeUnnullify

78 Order $ Opaleye.Order $ fmap (first g) . f . unsafeUnnullify