fradrive/src/Utils.hs

246 lines
6.6 KiB
Haskell

{-# LANGUAGE NoImplicitPrelude #-}
{-# LANGUAGE OverloadedStrings #-}
{-# LANGUAGE ScopedTypeVariables #-}
{-# LANGUAGE RankNTypes #-}
{-# LANGUAGE TypeSynonymInstances, FlexibleInstances, UndecidableInstances #-}
{-# LANGUAGE TypeFamilies, FlexibleContexts, ConstraintKinds #-}
{-# LANGUAGE QuasiQuotes #-}
module Utils
( module Utils
) where
import ClassyPrelude.Yesod
import Data.List (foldl)
import Data.Foldable as Fold
import qualified Data.Char as Char
import Utils.DB as Utils
import Utils.Common as Utils
import Text.Blaze (Markup, ToMarkup)
-- import Data.Map (Map)
-- import qualified Data.Map as Map
-- import qualified Data.List as List
import Control.Monad.Trans.Except (ExceptT(..), throwE, runExceptT)
import Control.Monad.Trans.Maybe (MaybeT(..))
import Control.Monad.Catch
import qualified Database.Esqueleto as E (Value, unValue)
-----------
-- Yesod --
-----------
newtype MsgRendererS site = MsgRenderer { render :: (forall msg. RenderMessage site msg => msg -> Text) }
getMsgRenderer :: forall m site. (MonadHandler m, HandlerSite m ~ site) => m (MsgRendererS site)
getMsgRenderer = do
mr <- getMessageRender
return $ MsgRenderer (mr . SomeMessage :: forall msg. RenderMessage site msg => msg -> Text)
---------------------
-- Text and String --
---------------------
tickmark :: IsString a => a
tickmark = fromString ""
text2Html :: Text -> Html
text2Html = toHtml -- prevents ambiguous types
toWgt :: (ToMarkup a, MonadBaseControl IO m, MonadThrow m, MonadIO m) =>
a -> WidgetT site m ()
toWgt = toWidget . toHtml
text2widget :: (MonadBaseControl IO m, MonadThrow m, MonadIO m) =>
Text -> WidgetT site m ()
text2widget t = [whamlet|#{t}|]
str2widget :: (MonadBaseControl IO m, MonadThrow m, MonadIO m) =>
String -> WidgetT site m ()
str2widget s = [whamlet|#{s}|]
withFragment :: ( Monad m
) => MForm m (a, WidgetT site IO ()) -> Markup -> MForm m (a, WidgetT site IO ())
withFragment form html = (flip fmap) form $ \(x, widget) -> (x, toWidget html >> widget)
uncamel :: String -> String -- "Model.Theme.CamelCaseThing" -> "camel-case-thing"
uncamel = ("theme-" ++) . reverse . foldl helper []
where
helper _ '.' = []
helper acc c
| Char.isSpace c = acc
| Char.isUpper c = Char.toLower c : '-' : acc
| otherwise = c : acc
camelSpace :: String -> String -- "Model.Theme.CamelCaseThing" -> "Camel Case Thing"
camelSpace = reverse . foldl helper []
where
helper _ '.' = []
helper acc c
| Char.isSpace c = acc
| Char.isUpper c = c : ' ' : acc
| otherwise = c : acc
-- Convert anything to Text, and I don't care how
class DisplayAble a where
display :: a -> Text
instance DisplayAble Text where
display = id
instance DisplayAble String where
display = pack
instance DisplayAble a => DisplayAble (Maybe a) where
display Nothing = ""
display (Just x) = display x
instance DisplayAble a => DisplayAble (E.Value a) where
display = display . E.unValue
-- The easy way out of UndecidableInstances (TypeFamilies would have been proper, but are much more complicated)
instance {-# OVERLAPPABLE #-} Show a => DisplayAble a where
display = pack . show
------------
-- Tuples --
------------
fst3 :: (a,b,c) -> a
fst3 (x,_,_) = x
snd3 :: (a,b,c) -> b
snd3 (_,y,_) = y
trd3 :: (a,b,c) -> c
trd3 (_,_,z) = z
-- Further projections are available via TemplateHaskell, defined in Utils.Common:
-- $(projN n m) :: (t1,..,tn) -> tm (for m<=n)
-- snd3 = $(projNI 3 2)
-----------
-- Lists --
-----------
-- notNull = not . null
----------
-- Maps --
----------
-----------
-- Maybe --
-----------
whenIsJust :: Monad m => Maybe a -> (a -> m ()) -> m ()
whenIsJust (Just x) f = f x
whenIsJust Nothing _ = return ()
maybeT :: Monad m => m a -> MaybeT m a -> m a
maybeT x m = runMaybeT m >>= maybe x return
catchIfMaybeT :: (MonadCatch m, Exception e) => (e -> Bool) -> m a -> MaybeT m a
catchIfMaybeT p act = catchIf p (lift act) (const mzero)
mcons :: Maybe a -> [a] -> [a]
mcons Nothing xs = xs
mcons (Just x) xs = x:xs
newtype NTop a = NTop a -- treat Nothing as Top for Ord (Maybe a); default implementation treats Nothing as bottom
instance Eq a => Eq (NTop (Maybe a)) where
(NTop x) == (NTop y) = x == y
instance Ord a => Ord (NTop (Maybe a)) where
compare (NTop Nothing) (NTop Nothing) = EQ
compare (NTop Nothing) _ = GT
compare _ (NTop Nothing) = LT
compare (NTop (Just x)) (NTop (Just y)) = compare x y
---------------
-- Exception --
---------------
maybeExceptT :: Monad m => e -> m (Maybe b) -> ExceptT e m b
maybeExceptT err act = lift act >>= maybe (throwE err) return
maybeMExceptT :: Monad m => (m e) -> m (Maybe b) -> ExceptT e m b
maybeMExceptT err act = lift act >>= maybe (lift err >>= throwE) return
whenExceptT :: Monad m => Bool -> e -> ExceptT e m ()
whenExceptT b err = when b $ throwE err
whenMExceptT :: Monad m => Bool -> (m e) -> ExceptT e m ()
whenMExceptT b err = when b $ lift err >>= throwE
guardExceptT :: Monad m => Bool -> e -> ExceptT e m ()
guardExceptT b err = unless b $ throwE err
guardMExceptT :: Monad m => Bool -> (m e) -> ExceptT e m ()
guardMExceptT b err = unless b $ lift err >>= throwE
exceptT :: Monad m => (e -> m b) -> (a -> m b) -> ExceptT e m a -> m b
exceptT f g = either f g <=< runExceptT
catchIfMExceptT :: (MonadCatch m, Exception e) => (e -> m e') -> (e -> Bool) -> m a -> ExceptT e' m a
catchIfMExceptT err p act = catchIf p (lift act) (throwE <=< lift . err)
------------
-- Monads --
------------
shortCircuitM :: Monad m => (a -> Bool) -> m a -> m a -> (a -> a -> a) -> m a
shortCircuitM sc mx my op = do
x <- mx
case sc x of
True -> return x
False -> op <$> pure x <*> my
guardM :: MonadPlus m => m Bool -> m ()
guardM f = guard =<< f
-- Some Utility Functions from Agda.Utils.Monad
-- | Monadic if-then-else.
ifM :: Monad m => m Bool -> m a -> m a -> m a
ifM c m m' =
do b <- c
if b then m else m'
-- | @ifNotM mc = ifM (not <$> mc)@
ifNotM :: Monad m => m Bool -> m a -> m a -> m a
ifNotM c = flip $ ifM c
-- | Lazy monadic conjunction.
and2M :: Monad m => m Bool -> m Bool -> m Bool
and2M ma mb = ifM ma mb (return False)
andM :: (Foldable f, Monad m) => f (m Bool) -> m Bool
andM = Fold.foldr and2M (return True)
allM :: (Functor f, Foldable f, Monad m) => f a -> (a -> m Bool) -> m Bool
allM xs f = andM $ fmap f xs
-- | Lazy monadic disjunction.
or2M :: Monad m => m Bool -> m Bool -> m Bool
or2M ma mb = ifM ma (return True) mb
orM :: (Foldable f, Monad m) => f (m Bool) -> m Bool
orM = Fold.foldr or2M (return False)
anyM :: (Functor f, Foldable f, Monad m) => f a -> (a -> m Bool) -> m Bool
anyM xs f = orM $ fmap f xs