graphql-engine/server/src-lib/Hasura/Prelude.hs
Antoine Leblanc 8a77386fcf server: IR for DB-DB joins
### Description

This PR adds the required IR for DB to DB joins, based on @paf31 and @0x777 's `feature/db-to-db` branch.

To do so, it also refactors the IR to introduce a new type parameter, `r`, which is used to recursively constructs the `v` parameter of remote QueryDBs. When collecting remote joins, we replace `r` with `Const Void`, indicating at the type level that there cannot be any leftover remote join.

Furthermore, this PR refactors IR.Select for readability, moves some code from IR.Root to IR.Select to avoid having to deal with circular dependencies, and makes it compile by adding `error` in all new cases in the execution pipeline.

The diff doesn't make it clear, but most of Select.hs is actually unchanged. Declarations have just been reordered by topic, in the following order:
- type declarations
- instance declarations
- type aliases
- constructor functions
- traverse functions

https://github.com/hasura/graphql-engine-mono/pull/1580

Co-authored-by: Phil Freeman <630306+paf31@users.noreply.github.com>
GitOrigin-RevId: bbdcb4119cec8bb3fc32f1294f91b8dea0728721
2021-06-17 23:13:05 +00:00

217 lines
8.3 KiB
Haskell

{-# OPTIONS_GHC -fno-warn-redundant-constraints #-}
{-# OPTIONS_GHC -fno-warn-orphans #-}
module Hasura.Prelude
( module M
, alphabet
, alphaNumerics
, onNothing
, onJust
, onLeft
, whenMaybe
, choice
, afold
, bsToTxt
, lbsToTxt
, txtToBs
, base64Decode
, spanMaybeM
, liftEitherM
, hoistMaybe
, hoistEither
, tshow
-- * Efficient coercions
, coerce
, findWithIndex
-- * Map-related utilities
, mapFromL
, mapKeys
, oMapFromL
-- * Measuring and working with moments and durations
, withElapsedTime
, startTimer
-- * Aeson options
, hasuraJSON
, module Data.Time.Clock.Units
) where
import Control.Applicative as M (Alternative (..), liftA2)
import Control.Arrow as M (first, second, (&&&), (***), (<<<), (>>>))
import Control.DeepSeq as M (NFData, deepseq, force)
import Control.Lens as M (ix, (%~))
import Control.Monad.Base as M
import Control.Monad.Except as M
import Control.Monad.Identity as M
import Control.Monad.Reader as M
import Control.Monad.State.Strict as M
import Control.Monad.Trans.Maybe as M (MaybeT (..))
import Control.Monad.Writer.Strict as M (MonadWriter (..), WriterT (..),
execWriterT, runWriterT)
import Data.Align as M (Semialign (align, alignWith))
import Data.Bool as M (bool)
import Data.Coerce
import Data.Data as M (Data (..))
import Data.Either as M (lefts, partitionEithers, rights)
import Data.Foldable as M (asum, fold, foldlM, foldrM, for_, toList,
traverse_)
import Data.Function as M (on, (&))
import Data.Functor as M (($>), (<&>))
import Data.Functor.Const as M (Const)
import Data.HashMap.Strict as M (HashMap)
import Data.HashMap.Strict.InsOrd as M (InsOrdHashMap)
import Data.HashSet as M (HashSet)
import Data.Hashable as M (Hashable)
import Data.List as M (find, findIndex, foldl', group,
intercalate, intersect, lookup, sort,
sortBy, sortOn, union, unionBy, (\\))
import Data.List.NonEmpty as M (NonEmpty (..), nonEmpty)
import Data.Maybe as M (catMaybes, fromMaybe, isJust, isNothing,
listToMaybe, mapMaybe, maybeToList)
import Data.Monoid as M (getAlt)
import Data.Ord as M (comparing)
import Data.Semigroup as M (Semigroup (..))
import Data.Sequence as M (Seq)
import Data.Sequence.NonEmpty as M (NESeq)
import Data.String as M (IsString)
import Data.Text as M (Text)
import Data.These as M (These (..), fromThese, mergeThese,
mergeTheseWith, partitionThese, these)
import Data.Time.Clock.Units
import Data.Traversable as M (for)
import Data.Void as M (Void, absurd)
import Data.Word as M (Word64)
import GHC.Generics as M (Generic)
import Prelude as M hiding (fail, init, lookup)
import Test.QuickCheck.Arbitrary.Generic as M
import Text.Read as M (readEither, readMaybe)
import qualified Data.Aeson as J
import qualified Data.Aeson.Casing as J
import qualified Data.ByteString as B
import qualified Data.ByteString.Base64.Lazy as Base64
import qualified Data.ByteString.Lazy as BL
import qualified Data.HashMap.Strict as Map
import qualified Data.HashMap.Strict.InsOrd as OMap
import qualified Data.Text as T
import qualified Data.Text.Encoding as TE
import qualified Data.Text.Encoding.Error as TE
import qualified GHC.Clock as Clock
import qualified Test.QuickCheck as QC
alphabet :: String
alphabet = ['a'..'z'] ++ ['A'..'Z']
alphaNumerics :: String
alphaNumerics = alphabet ++ "0123456789"
instance Arbitrary Text where
arbitrary = T.pack <$> QC.listOf (QC.elements alphaNumerics)
onNothing :: Applicative m => Maybe a -> m a -> m a
onNothing m act = maybe act pure m
onJust :: Applicative m => Maybe a -> (a -> m ()) -> m ()
onJust m action = maybe (pure ()) action m
onLeft :: Applicative m => Either e a -> (e -> m a) -> m a
onLeft e f = either f pure e
whenMaybe :: Applicative m => Bool -> m a -> m (Maybe a)
whenMaybe True = fmap Just
whenMaybe False = const $ pure Nothing
choice :: Alternative f => [f a] -> f a
choice = asum
afold :: (Foldable t, Alternative f) => t a -> f a
afold = getAlt . foldMap pure
bsToTxt :: B.ByteString -> Text
bsToTxt = TE.decodeUtf8With TE.lenientDecode
lbsToTxt :: BL.ByteString -> Text
lbsToTxt = bsToTxt . BL.toStrict
txtToBs :: Text -> B.ByteString
txtToBs = TE.encodeUtf8
base64Decode :: Text -> BL.ByteString
base64Decode =
Base64.decodeLenient . BL.fromStrict . txtToBs
-- Like `liftEither`, but accepts a monadic action
liftEitherM :: MonadError e m => m (Either e a) -> m a
liftEitherM action = action >>= liftEither
-- Like 'span', but monadic and with a function that produces 'Maybe' instead of 'Bool'
spanMaybeM
:: (Foldable f, Monad m)
=> (a -> m (Maybe b)) -> f a -> m ([b], [a])
spanMaybeM f = go . toList
where
go [] = pure ([], [])
go l@(x:xs) = f x >>= \case
Just y -> first (y:) <$> go xs
Nothing -> pure ([], l)
findWithIndex :: (a -> Bool) -> [a] -> Maybe (a, Int)
findWithIndex p l = do
v <- find p l
i <- findIndex p l
pure (v, i)
-- TODO (from master): Move to Data.HashMap.Strict.Extended; rename to fromListWith?
mapFromL :: (Eq k, Hashable k) => (a -> k) -> [a] -> Map.HashMap k a
mapFromL f = Map.fromList . map (\v -> (f v, v))
-- | re-key a map. In the case that @f@ is not injective you may end up with a
-- smaller map than what you started with.
--
-- This may be a code smell.
mapKeys :: (Eq k2, Hashable k2) => (k1 -> k2) -> Map.HashMap k1 a -> Map.HashMap k2 a
mapKeys f = Map.fromList . map (first f) . Map.toList
oMapFromL :: (Eq k, Hashable k) => (a -> k) -> [a] -> InsOrdHashMap k a
oMapFromL f = OMap.fromList . map (\v -> (f v, v))
-- | Time an IO action, returning the time with microsecond precision. The
-- result of the input action will be evaluated to WHNF.
--
-- The result 'DiffTime' is guarenteed to be >= 0.
withElapsedTime :: MonadIO m => m a -> m (DiffTime, a)
withElapsedTime ma = do
bef <- liftIO Clock.getMonotonicTimeNSec
!a <- ma
aft <- liftIO Clock.getMonotonicTimeNSec
let !dur = nanoseconds $ fromIntegral (aft - bef)
return (dur, a)
-- | Start timing and return an action to return the elapsed time since 'startTimer' was called.
--
-- @
-- timer <- startTimer
-- someStuffToTime
-- elapsed <- timer
-- moreStuff
-- elapsedBoth <- timer
-- @
startTimer :: (MonadIO m, MonadIO n) => m (n DiffTime)
startTimer = do
!bef <- liftIO Clock.getMonotonicTimeNSec
return $ do
aft <- liftIO Clock.getMonotonicTimeNSec
return $ nanoseconds $ fromIntegral (aft - bef)
-- copied from http://hackage.haskell.org/package/errors-2.3.0/docs/src/Control.Error.Util.html#hoistMaybe
hoistMaybe :: Applicative m => Maybe b -> MaybeT m b
hoistMaybe = MaybeT . pure
hoistEither :: Applicative m => Either e a -> ExceptT e m a
hoistEither = ExceptT . pure
tshow :: Show a => a -> Text
tshow = T.pack . show
hasuraJSON :: J.Options
hasuraJSON = J.aesonPrefix J.snakeCase