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module Main where | |
import Prelude | |
import Control.Parallel (class Parallel, parallel, sequential) | |
import Data.Maybe (Maybe(..)) | |
import Data.Symbol (class IsSymbol, SProxy(..)) | |
import Effect (Effect) | |
import Effect.Class.Console (logShow) | |
import Prim.Row as Row | |
import Prim.RowList as RL | |
import Record as Record | |
import Type.Data.RowList (RLProxy(..)) | |
---------------------------------------------------------------- | |
main :: Effect Unit | |
main = do | |
logShow $ sequenceRow { x: Just 123, y: Just "abc" } | |
logShow $ sequenceRow { x: Just 123, y: Nothing :: Maybe String } | |
logShow $ sequenceRow { x: [1, 2, 3], y: ["a", "b"] } | |
---------------------------------------------------------------- | |
class RowTraversable list xs ys m f | list -> ys m where | |
traverseRow :: (RLProxy list) -> (m ~> f) -> { | xs } -> f { | ys } | |
instance rowTraversableNil :: Applicative f => RowTraversable RL.Nil xs () m f where | |
traverseRow _ _ _ = pure {} | |
instance rowTraversableCons :: | |
( IsSymbol key | |
, Row.Cons key (m a) xs' xs | |
, Row.Cons key a ys' ys | |
, Row.Lacks key ys' | |
, RowTraversable tail xs ys' m f | |
, Applicative f | |
) => RowTraversable (RL.Cons key (m a) tail) xs ys m f where | |
traverseRow _ f obj = Record.insert key <$> f (Record.get key obj) <*> traverseRow tail f obj | |
where | |
key = SProxy :: SProxy key | |
tail = RLProxy :: RLProxy tail | |
sequenceRow | |
:: forall rowList mr r m | |
. RL.RowToList mr rowList | |
=> RowTraversable rowList mr r m m | |
=> { | mr } -> m { | r } | |
sequenceRow = traverseRow (RLProxy :: RLProxy rowList) identity | |
props | |
:: forall rowList mr r m f | |
. RL.RowToList mr rowList | |
=> RowTraversable rowList mr r m f | |
=> Parallel f m | |
=> { | mr } -> m { | r } | |
props = sequential <<< traverseRow (RLProxy :: RLProxy rowList) parallel |
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