Copyright	Copyright © 2015 PivotCloud, Inc.
License	MIT
Maintainer	Lars Kuhtz <lkuhtz@pivotmail.com>
Stability	experimental
Safe Haskell	None
Language	Haskell2010

Configuration.Utils.Monoid

Description

The distinction between appending on the left and appending on the right is important for monoids that are sensitive to ordering such as List. It is also of relevance for monoids with set semantics with non-extensional equality such as HashMap.

Synopsis

Documentation

data LeftMonoidalUpdate α Source

Update a value by appending on the left. Under normal circumstances you'll never use this type directly but only its FromJSON instance. See the leftMonoidalUpdate for an example.

Instances

Monoid α => Monoid (LeftMonoidalUpdate α)
(FromJSON α, Monoid α) => FromJSON (LeftMonoidalUpdate α -> LeftMonoidalUpdate α)

leftMonoidalUpdate :: Iso (LeftMonoidalUpdate α) (LeftMonoidalUpdate β) α β Source

Update a value by appending on the left.

newtype RoutingTable = RoutingTable { _routingTableMap ∷ HashMap T.Text T.Text }

$(makeLenses ''RoutingTable)

instance FromJSON (RoutingTable → RoutingTable) where
    parseJSON = withObject "RoutingTable" $ \o → id
        <$< routingTableMap . from leftMonoidalUpdate %.: "route_map" % o

fromLeftMonoidalUpdate :: Iso α β (LeftMonoidalUpdate α) (LeftMonoidalUpdate β) Source

This is the same as from leftMonoidalUpdate but doesn't depend on the lens Library.

pLeftMonoidalUpdate :: Monoid α => Parser α -> MParser α Source

Update a value by appending on the left.

newtype RoutingTable = RoutingTable { _routingTableMap ∷ HashMap T.Text T.Text }

$(makeLenses ''RoutingTable)

pRoutingTable ∷ MParser RoutingTable
pRoutingTable = routingTableMap %:: pLeftMonoidalUpdate pRoute
  where
    pRoute = option (eitherReader readRoute)
        % long "route"
        <> help "add a route to the routing table; the APIROUTE part must not contain a colon character"
        <> metavar "APIROUTE:APIURL"

    readRoute s = case break (== ':') s of
        (a,':':b) → fmapL T.unpack $ do
            validateNonEmpty "APIROUTE" a
            validateHttpOrHttpsUrl "APIURL" b
            return $ HM.singleton (T.pack a) (T.pack b)
        _ → Left "missing colon between APIROUTE and APIURL"

    fmapL f = either (Left . f) Right

data RightMonoidalUpdate α Source

Update a value by appending on the right. Under normal circumstances you'll never use this type directly but only its FromJSON instance. See the leftMonoidalUpdate for an example.

Instances

Monoid α => Monoid (RightMonoidalUpdate α)
(FromJSON α, Monoid α) => FromJSON (RightMonoidalUpdate α -> RightMonoidalUpdate α)

rightMonoidalUpdate :: Iso (RightMonoidalUpdate α) (RightMonoidalUpdate β) α β Source

Update a value by appending on the right. See leftMonoidalUpdate for an usage example.

fromRightMonoidalUpdate :: Iso α β (RightMonoidalUpdate α) (RightMonoidalUpdate β) Source

This is the same as from rightMonoidalUpdate but doesn't depend on the lens Library.

pRightMonoidalUpdate :: Monoid α => Parser α -> MParser α Source

Update a value by appending on the right. See pLeftMonoidalUpdate for an usage example.