graphql-engine/server/src-lib/Hasura/Prelude.hs
Tom Harding 178e452b6b Use witherable, remove catMaybes/mapMaybe
PR-URL: https://github.com/hasura/graphql-engine-mono/pull/5250
GitOrigin-RevId: 5f0a582b3a853d2dbcce20e88c17970290625fc6
2022-07-29 14:53:16 +00:00

347 lines
9.7 KiB
Haskell

{-# OPTIONS_GHC -fno-warn-orphans #-}
{-# OPTIONS_GHC -fno-warn-redundant-constraints #-}
module Hasura.Prelude
( module M,
alphabet,
alphaNumerics,
catMaybes,
onNothing,
onNothingM,
onJust,
withJust,
mapMaybe,
maybeToEither,
eitherToMaybe,
onLeft,
mapLeft,
whenMaybe,
choice,
afold,
bsToTxt,
lbsToTxt,
txtToBs,
base64Decode,
spanMaybeM,
liftEitherM,
hoistMaybe,
hoistEither,
readJson,
tshow,
hashNub,
-- * Trace debugging
ltrace,
ltraceM,
traceToFile,
traceToFileM,
-- * Efficient coercions
coerce,
findWithIndex,
-- * Map-related utilities
mapFromL,
oMapFromL,
-- * Measuring and working with moments and durations
withElapsedTime,
startTimer,
-- * Aeson options
hasuraJSON,
-- * NonEmpty.Seq
nonEmptySeqToNonEmptyList,
-- * Extensions to @Data.Foldable@
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.Aeson qualified as J
import Data.Aeson.Casing qualified as J
import Data.Bool as M (bool)
import Data.ByteString qualified as B
import Data.ByteString.Base64.Lazy qualified as Base64
import Data.ByteString.Lazy qualified as BL
import Data.Coerce
import Data.Data as M (Data (..))
import Data.Either as M (lefts, partitionEithers, rights)
import Data.Foldable as M
( asum,
fold,
foldMap',
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, mapKeys)
import Data.HashMap.Strict qualified as Map
import Data.HashMap.Strict.InsOrd as M (InsOrdHashMap)
import Data.HashMap.Strict.InsOrd qualified as OMap
import Data.HashSet as M (HashSet)
import Data.HashSet qualified as HSet
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
( fromMaybe,
isJust,
isNothing,
listToMaybe,
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.Sequence.NonEmpty qualified as NESeq
import Data.String as M (IsString)
import Data.Text as M (Text)
import Data.Text qualified as T
import Data.Text.Encoding qualified as TE
import Data.Text.Encoding.Error qualified as TE
import Data.Text.Lazy qualified as TL
import Data.Text.Lazy.IO qualified as TLIO
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 Debug.Trace qualified as Debug (trace, traceM)
import GHC.Clock qualified as Clock
import GHC.Generics as M (Generic)
import System.IO.Unsafe (unsafePerformIO) -- for custom trace functions
import Text.Pretty.Simple qualified as PS
import Text.Read as M (readEither, readMaybe)
import Witherable (catMaybes, mapMaybe)
import Prelude as M hiding (fail, init, lookup)
alphabet :: String
alphabet = ['a' .. 'z'] ++ ['A' .. 'Z']
alphaNumerics :: String
alphaNumerics = alphabet ++ "0123456789"
onNothing :: Applicative m => Maybe a -> m a -> m a
onNothing m act = maybe act pure m
onNothingM :: Monad m => m (Maybe a) -> m a -> m a
onNothingM m act = m >>= (`onNothing` act)
onJust :: Applicative m => Maybe a -> (a -> m ()) -> m ()
onJust m action = maybe (pure ()) action m
withJust :: Applicative m => Maybe a -> (a -> m (Maybe b)) -> m (Maybe b)
withJust m action = maybe (pure Nothing) action m
-- | Transform a 'Maybe' into an 'Either' given a default value.
--
-- > maybeToEither def Nothing == Left def
-- > maybeToEither _def (Just b) == Right b
maybeToEither :: a -> Maybe b -> Either a b
maybeToEither a = maybe (Left a) Right
-- | Convert an 'Either' to a 'Maybe', forgetting the 'Left' values.
--
-- > eitherToMaybe (Left a) == Nothing
-- > eitherToMaybe (Right b) == Just b
eitherToMaybe :: Either a b -> Maybe b
eitherToMaybe = either (const Nothing) Just
onLeft :: Applicative m => Either e a -> (e -> m a) -> m a
onLeft e f = either f pure e
mapLeft :: (e1 -> e2) -> Either e1 a -> Either e2 a
mapLeft f (Left e1) = Left (f e1)
mapLeft _ (Right a) = Right a
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 main): 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))
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)
-- | Upgrade a 'Maybe' to a 'MaybeT'.
--
-- cf. 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
-- | Upgrade an 'Either' to an 'ExceptT'.
--
-- cf. http://hackage.haskell.org/package/errors-2.3.0/docs/src/Control.Error.Util.html#hoistEither
hoistEither :: Applicative m => Either e a -> ExceptT e m a
hoistEither = ExceptT . pure
tshow :: Show a => a -> Text
tshow = T.pack . show
readJson :: (J.FromJSON a) => String -> Either String a
readJson = J.eitherDecodeStrict . txtToBs . T.pack
-- | Customized 'J.Options' which apply "snake case" to Generic or Template
-- Haskell JSON derivations.
--
-- For example, a Haskell field @fooBar@ would be de/serialized from/to JSON as
-- @foo_bar@.
hasuraJSON :: J.Options
hasuraJSON = J.aesonPrefix J.snakeCase
-- Fancy trace debugging
-- | Labeled, prettified traceShowId
ltrace :: Show a => String -> a -> a
ltrace lbl x = Debug.trace (lbl <> ": " <> TL.unpack (PS.pShow x)) x
{-# WARNING ltrace "ltrace left in code" #-}
-- | Labeled, prettified traceShowM
ltraceM :: Applicative m => Show a => String -> a -> m ()
ltraceM lbl x = Debug.traceM (lbl <> ": " <> TL.unpack (PS.pShow x))
{-# WARNING ltraceM "ltraceM left in code" #-}
-- | Trace a prettified value to a file
traceToFile :: Show a => FilePath -> a -> a
traceToFile filepath x =
Debug.trace
("tracing to " <> filepath)
(unsafePerformIO (TLIO.writeFile filepath (PS.pShowNoColor x) $> x))
{-# WARNING traceToFile "traceToFile left in code" #-}
-- | Trace a prettified value to a file in an Applicative context
traceToFileM :: Applicative m => Show a => FilePath -> a -> m ()
traceToFileM filepath x =
Debug.traceM $
unwords
[ "tracing to",
filepath,
show $ unsafePerformIO $ TLIO.writeFile filepath $ PS.pShowNoColor x
]
{-# WARNING traceToFileM "traceToFileM left in code" #-}
-- | Remove duplicates from a list. Like 'nub' but runs in @O(n * log_16(n))@
-- time and requires 'Hashable' and `Eq` instances. hashNub is faster than
-- ordNub when there're not so many different values in the list.
--
-- >>> hashNub [1,3,2,9,4,1,5,7,3,3,1,2,5,4,3,2,1,0]
-- [0,1,2,3,4,5,7,9]
hashNub :: (Hashable a, Eq a) => [a] -> [a]
hashNub = HSet.toList . HSet.fromList
-- | Convert a non-empty sequence to a non-empty list.
nonEmptySeqToNonEmptyList :: NESeq a -> NonEmpty a
nonEmptySeqToNonEmptyList (x NESeq.:<|| xs) =
x M.:| toList xs