{-# LANGUAGE DeriveGeneric #-}{-# LANGUAGE GeneralizedNewtypeDeriving #-}{-# LANGUAGE NoImplicitPrelude #-}{-# LANGUAGE PolyKinds #-}{-# LANGUAGE ScopedTypeVariables #-}{-# LANGUAGE Trustworthy #-}------------------------------------------------------------------------------- |-- Module : GHC.Internal.Data.Monoid-- Copyright : (c) Andy Gill 2001,-- (c) Oregon Graduate Institute of Science and Technology, 2001-- License : BSD-style (see the file libraries/base/LICENSE)---- Maintainer : libraries@haskell.org-- Stability : stable-- Portability : portable---- A type @a@ is a 'Monoid' if it provides an associative function ('<>')-- that lets you combine any two values of type @a@ into one, and a neutral-- element (`mempty`) such that---- > a <> mempty == mempty <> a == a---- A 'Monoid' is a 'Semigroup' with the added requirement of a neutral element.-- Thus any 'Monoid' is a 'Semigroup', but not the other way around.---- ==== __Examples__---- The 'Sum' monoid is defined by the numerical addition operator and `0` as neutral element:---- >>> import Data.Int (Int)-- >>> mempty :: Sum Int-- Sum {getSum = 0}-- >>> Sum 1 <> Sum 2 <> Sum 3 <> Sum 4 :: Sum Int-- Sum {getSum = 10}---- We can combine multiple values in a list into a single value using the `mconcat` function.-- Note that we have to specify the type here since 'Int' is a monoid under several different-- operations:---- >>> mconcat [1,2,3,4] :: Sum Int-- Sum {getSum = 10}-- >>> mconcat [] :: Sum Int-- Sum {getSum = 0}---- Another valid monoid instance of 'Int' is 'Product' It is defined by multiplication-- and `1` as neutral element:---- >>> Product 1 <> Product 2 <> Product 3 <> Product 4 :: Product Int-- Product {getProduct = 24}-- >>> mconcat [1,2,3,4] :: Product Int-- Product {getProduct = 24}-- >>> mconcat [] :: Product Int-- Product {getProduct = 1}---------------------------------------------------------------------------------moduleGHC.Internal.Data.Monoid (-- * 'Monoid' typeclassMonoid (..),(<>) ,Dual (..),Endo (..),-- * 'Bool' wrappersAll (..),Any (..),-- * 'Num' wrappersSum (..),Product (..),-- * 'Maybe' wrappers-- $MaybeExamplesFirst (..),Last (..),-- * 'Alternative' wrapperAlt (..),-- * 'Applicative' wrapperAp (..))where-- $setup-- >>> import Data.Int-- Push down the module in the dependency hierarchy.importGHC.Internal.Base hiding(Any )importGHC.Internal.Enum importGHC.Internal.Generics importGHC.Internal.Num importGHC.Internal.Read importGHC.Internal.Show importGHC.Internal.Control.Monad.Fail (MonadFail )importGHC.Internal.Data.Semigroup.Internal -- $MaybeExamples-- To implement @find@ or @findLast@ on any 'Data.Foldable.Foldable':---- @-- findLast :: Foldable t => (a -> Bool) -> t a -> Maybe a-- findLast pred = getLast . foldMap (\x -> if pred x-- then Last (Just x)-- else Last Nothing)-- @---- Much of 'Data.Map.Lazy.Map's interface can be implemented with-- 'Data.Map.Lazy.alter'. Some of the rest can be implemented with a new-- 'Data.Map.Lazy.alterF' function and either 'First' or 'Last':---- > alterF :: (Functor f, Ord k) =>-- > (Maybe a -> f (Maybe a)) -> k -> Map k a -> f (Map k a)-- >-- > instance Monoid a => Functor ((,) a) -- from GHC.Internal.Data.Functor---- @-- insertLookupWithKey :: Ord k => (k -> v -> v -> v) -> k -> v-- -> Map k v -> (Maybe v, Map k v)-- insertLookupWithKey combine key value =-- Arrow.first getFirst . 'Data.Map.Lazy.alterF' doChange key-- where-- doChange Nothing = (First Nothing, Just value)-- doChange (Just oldValue) =-- (First (Just oldValue),-- Just (combine key value oldValue))-- @-- | Maybe monoid returning the leftmost non-'Nothing' value.---- @'First' a@ is isomorphic to @'Alt' 'Maybe' a@, but precedes it-- historically.---- Beware that @Data.Monoid.@'First' is different from-- @Data.Semigroup.@'Data.Semigroup.First'. The former returns the first non-'Nothing',-- so @Data.Monoid.First Nothing <> x = x@. The latter simply returns the first value,-- thus @Data.Semigroup.First Nothing <> x = Data.Semigroup.First Nothing@.---- ==== __Examples__---- >>> First (Just "hello") <> First Nothing <> First (Just "world")-- First {getFirst = Just "hello"}---- >>> First Nothing <> mempty-- First {getFirst = Nothing}newtypeFirst a =First {forall a. First a -> Maybe a
getFirst ::Maybe a }deriving(First a -> First a -> Bool
(First a -> First a -> Bool)
-> (First a -> First a -> Bool) -> Eq (First a)
forall a. Eq a => First a -> First a -> Bool
forall a. (a -> a -> Bool) -> (a -> a -> Bool) -> Eq a
$c== :: forall a. Eq a => First a -> First a -> Bool
== :: First a -> First a -> Bool
$c/= :: forall a. Eq a => First a -> First a -> Bool
/= :: First a -> First a -> Bool
Eq -- ^ @since base-2.01,Eq (First a)
Eq (First a) =>
(First a -> First a -> Ordering)
-> (First a -> First a -> Bool)
-> (First a -> First a -> Bool)
-> (First a -> First a -> Bool)
-> (First a -> First a -> Bool)
-> (First a -> First a -> First a)
-> (First a -> First a -> First a)
-> Ord (First a)
First a -> First a -> Bool
First a -> First a -> Ordering
First a -> First a -> First a
forall a.
Eq a =>
(a -> a -> Ordering)
-> (a -> a -> Bool)
-> (a -> a -> Bool)
-> (a -> a -> Bool)
-> (a -> a -> Bool)
-> (a -> a -> a)
-> (a -> a -> a)
-> Ord a
forall a. Ord a => Eq (First a)
forall a. Ord a => First a -> First a -> Bool
forall a. Ord a => First a -> First a -> Ordering
forall a. Ord a => First a -> First a -> First a
$ccompare :: forall a. Ord a => First a -> First a -> Ordering
compare :: First a -> First a -> Ordering
$c< :: forall a. Ord a => First a -> First a -> Bool
< :: First a -> First a -> Bool
$c<= :: forall a. Ord a => First a -> First a -> Bool
<= :: First a -> First a -> Bool
$c> :: forall a. Ord a => First a -> First a -> Bool
> :: First a -> First a -> Bool
$c>= :: forall a. Ord a => First a -> First a -> Bool
>= :: First a -> First a -> Bool
$cmax :: forall a. Ord a => First a -> First a -> First a
max :: First a -> First a -> First a
$cmin :: forall a. Ord a => First a -> First a -> First a
min :: First a -> First a -> First a
Ord -- ^ @since base-2.01,ReadPrec [First a]
ReadPrec (First a)
Int -> ReadS (First a)
ReadS [First a]
(Int -> ReadS (First a))
-> ReadS [First a]
-> ReadPrec (First a)
-> ReadPrec [First a]
-> Read (First a)
forall a. Read a => ReadPrec [First a]
forall a. Read a => ReadPrec (First a)
forall a. Read a => Int -> ReadS (First a)
forall a. Read a => ReadS [First a]
forall a.
(Int -> ReadS a)
-> ReadS [a] -> ReadPrec a -> ReadPrec [a] -> Read a
$creadsPrec :: forall a. Read a => Int -> ReadS (First a)
readsPrec :: Int -> ReadS (First a)
$creadList :: forall a. Read a => ReadS [First a]
readList :: ReadS [First a]
$creadPrec :: forall a. Read a => ReadPrec (First a)
readPrec :: ReadPrec (First a)
$creadListPrec :: forall a. Read a => ReadPrec [First a]
readListPrec :: ReadPrec [First a]
Read -- ^ @since base-2.01,Int -> First a -> ShowS
[First a] -> ShowS
First a -> String
(Int -> First a -> ShowS)
-> (First a -> String) -> ([First a] -> ShowS) -> Show (First a)
forall a. Show a => Int -> First a -> ShowS
forall a. Show a => [First a] -> ShowS
forall a. Show a => First a -> String
forall a.
(Int -> a -> ShowS) -> (a -> String) -> ([a] -> ShowS) -> Show a
$cshowsPrec :: forall a. Show a => Int -> First a -> ShowS
showsPrec :: Int -> First a -> ShowS
$cshow :: forall a. Show a => First a -> String
show :: First a -> String
$cshowList :: forall a. Show a => [First a] -> ShowS
showList :: [First a] -> ShowS
Show -- ^ @since base-2.01,(forall x. First a -> Rep (First a) x)
-> (forall x. Rep (First a) x -> First a) -> Generic (First a)
forall x. Rep (First a) x -> First a
forall x. First a -> Rep (First a) x
forall a.
(forall x. a -> Rep a x) -> (forall x. Rep a x -> a) -> Generic a
forall a x. Rep (First a) x -> First a
forall a x. First a -> Rep (First a) x
$cfrom :: forall a x. First a -> Rep (First a) x
from :: forall x. First a -> Rep (First a) x
$cto :: forall a x. Rep (First a) x -> First a
to :: forall x. Rep (First a) x -> First a
Generic -- ^ @since base-4.7.0.0,(forall a. First a -> Rep1 First a)
-> (forall a. Rep1 First a -> First a) -> Generic1 First
forall a. Rep1 First a -> First a
forall a. First a -> Rep1 First a
forall k (f :: k -> *).
(forall (a :: k). f a -> Rep1 f a)
-> (forall (a :: k). Rep1 f a -> f a) -> Generic1 f
$cfrom1 :: forall a. First a -> Rep1 First a
from1 :: forall a. First a -> Rep1 First a
$cto1 :: forall a. Rep1 First a -> First a
to1 :: forall a. Rep1 First a -> First a
Generic1 -- ^ @since base-4.7.0.0,(forall a b. (a -> b) -> First a -> First b)
-> (forall a b. a -> First b -> First a) -> Functor First
forall a b. a -> First b -> First a
forall a b. (a -> b) -> First a -> First b
forall (f :: * -> *).
(forall a b. (a -> b) -> f a -> f b)
-> (forall a b. a -> f b -> f a) -> Functor f
$cfmap :: forall a b. (a -> b) -> First a -> First b
fmap :: forall a b. (a -> b) -> First a -> First b
$c<$ :: forall a b. a -> First b -> First a
<$ :: forall a b. a -> First b -> First a
Functor -- ^ @since base-4.8.0.0,Functor First
Functor First =>
(forall a. a -> First a)
-> (forall a b. First (a -> b) -> First a -> First b)
-> (forall a b c. (a -> b -> c) -> First a -> First b -> First c)
-> (forall a b. First a -> First b -> First b)
-> (forall a b. First a -> First b -> First a)
-> Applicative First
forall a. a -> First a
forall a b. First a -> First b -> First a
forall a b. First a -> First b -> First b
forall a b. First (a -> b) -> First a -> First b
forall a b c. (a -> b -> c) -> First a -> First b -> First c
forall (f :: * -> *).
Functor f =>
(forall a. a -> f a)
-> (forall a b. f (a -> b) -> f a -> f b)
-> (forall a b c. (a -> b -> c) -> f a -> f b -> f c)
-> (forall a b. f a -> f b -> f b)
-> (forall a b. f a -> f b -> f a)
-> Applicative f
$cpure :: forall a. a -> First a
pure :: forall a. a -> First a
$c<*> :: forall a b. First (a -> b) -> First a -> First b
<*> :: forall a b. First (a -> b) -> First a -> First b
$cliftA2 :: forall a b c. (a -> b -> c) -> First a -> First b -> First c
liftA2 :: forall a b c. (a -> b -> c) -> First a -> First b -> First c
$c*> :: forall a b. First a -> First b -> First b
*> :: forall a b. First a -> First b -> First b
$c<* :: forall a b. First a -> First b -> First a
<* :: forall a b. First a -> First b -> First a
Applicative -- ^ @since base-4.8.0.0,Applicative First
Applicative First =>
(forall a b. First a -> (a -> First b) -> First b)
-> (forall a b. First a -> First b -> First b)
-> (forall a. a -> First a)
-> Monad First
forall a. a -> First a
forall a b. First a -> First b -> First b
forall a b. First a -> (a -> First b) -> First b
forall (m :: * -> *).
Applicative m =>
(forall a b. m a -> (a -> m b) -> m b)
-> (forall a b. m a -> m b -> m b)
-> (forall a. a -> m a)
-> Monad m
$c>>= :: forall a b. First a -> (a -> First b) -> First b
>>= :: forall a b. First a -> (a -> First b) -> First b
$c>> :: forall a b. First a -> First b -> First b
>> :: forall a b. First a -> First b -> First b
$creturn :: forall a. a -> First a
return :: forall a. a -> First a
Monad -- ^ @since base-4.8.0.0)-- | @since base-4.9.0.0instanceSemigroup (First a )whereFirst Maybe a
Nothing <> :: First a -> First a -> First a
<> First a
b =First a
b First a
a <> First a
_=First a
a stimes :: forall b. Integral b => b -> First a -> First a
stimes =b -> First a -> First a
forall b a. (Integral b, Monoid a) => b -> a -> a
stimesIdempotentMonoid sconcat :: NonEmpty (First a) -> First a
sconcat (first :: First a
first @(First Maybe a
m ):| [First a]
rest )|Maybe a
Nothing <-Maybe a
m =[First a] -> First a
forall a. Monoid a => [a] -> a
mconcat [First a]
rest |Bool
otherwise =First a
first -- | @since base-2.01instanceMonoid (First a )wheremempty :: First a
mempty =Maybe a -> First a
forall a. Maybe a -> First a
First Maybe a
forall a. Maybe a
Nothing -- | Maybe monoid returning the rightmost non-'Nothing' value.---- @'Last' a@ is isomorphic to @'Dual' ('First' a)@, and thus to-- @'Dual' ('Alt' 'Maybe' a)@---- @Data.Semigroup.@'Data.Semigroup.Last'. The former returns the last non-'Nothing',-- so @x <> Data.Monoid.Last Nothing = x@. The latter simply returns the last value,-- thus @x <> Data.Semigroup.Last Nothing = Data.Semigroup.Last Nothing@.---- ==== __Examples__---- >>> Last (Just "hello") <> Last Nothing <> Last (Just "world")-- Last {getLast = Just "world"}---- >>> Last Nothing <> mempty-- Last {getLast = Nothing}newtypeLast a =Last {forall a. Last a -> Maybe a
getLast ::Maybe a }deriving(Last a -> Last a -> Bool
(Last a -> Last a -> Bool)
-> (Last a -> Last a -> Bool) -> Eq (Last a)
forall a. Eq a => Last a -> Last a -> Bool
forall a. (a -> a -> Bool) -> (a -> a -> Bool) -> Eq a
$c== :: forall a. Eq a => Last a -> Last a -> Bool
== :: Last a -> Last a -> Bool
$c/= :: forall a. Eq a => Last a -> Last a -> Bool
/= :: Last a -> Last a -> Bool
Eq -- ^ @since base-2.01,Eq (Last a)
Eq (Last a) =>
(Last a -> Last a -> Ordering)
-> (Last a -> Last a -> Bool)
-> (Last a -> Last a -> Bool)
-> (Last a -> Last a -> Bool)
-> (Last a -> Last a -> Bool)
-> (Last a -> Last a -> Last a)
-> (Last a -> Last a -> Last a)
-> Ord (Last a)
Last a -> Last a -> Bool
Last a -> Last a -> Ordering
Last a -> Last a -> Last a
forall a.
Eq a =>
(a -> a -> Ordering)
-> (a -> a -> Bool)
-> (a -> a -> Bool)
-> (a -> a -> Bool)
-> (a -> a -> Bool)
-> (a -> a -> a)
-> (a -> a -> a)
-> Ord a
forall a. Ord a => Eq (Last a)
forall a. Ord a => Last a -> Last a -> Bool
forall a. Ord a => Last a -> Last a -> Ordering
forall a. Ord a => Last a -> Last a -> Last a
$ccompare :: forall a. Ord a => Last a -> Last a -> Ordering
compare :: Last a -> Last a -> Ordering
$c< :: forall a. Ord a => Last a -> Last a -> Bool
< :: Last a -> Last a -> Bool
$c<= :: forall a. Ord a => Last a -> Last a -> Bool
<= :: Last a -> Last a -> Bool
$c> :: forall a. Ord a => Last a -> Last a -> Bool
> :: Last a -> Last a -> Bool
$c>= :: forall a. Ord a => Last a -> Last a -> Bool
>= :: Last a -> Last a -> Bool
$cmax :: forall a. Ord a => Last a -> Last a -> Last a
max :: Last a -> Last a -> Last a
$cmin :: forall a. Ord a => Last a -> Last a -> Last a
min :: Last a -> Last a -> Last a
Ord -- ^ @since base-2.01,ReadPrec [Last a]
ReadPrec (Last a)
Int -> ReadS (Last a)
ReadS [Last a]
(Int -> ReadS (Last a))
-> ReadS [Last a]
-> ReadPrec (Last a)
-> ReadPrec [Last a]
-> Read (Last a)
forall a. Read a => ReadPrec [Last a]
forall a. Read a => ReadPrec (Last a)
forall a. Read a => Int -> ReadS (Last a)
forall a. Read a => ReadS [Last a]
forall a.
(Int -> ReadS a)
-> ReadS [a] -> ReadPrec a -> ReadPrec [a] -> Read a
$creadsPrec :: forall a. Read a => Int -> ReadS (Last a)
readsPrec :: Int -> ReadS (Last a)
$creadList :: forall a. Read a => ReadS [Last a]
readList :: ReadS [Last a]
$creadPrec :: forall a. Read a => ReadPrec (Last a)
readPrec :: ReadPrec (Last a)
$creadListPrec :: forall a. Read a => ReadPrec [Last a]
readListPrec :: ReadPrec [Last a]
Read -- ^ @since base-2.01,Int -> Last a -> ShowS
[Last a] -> ShowS
Last a -> String
(Int -> Last a -> ShowS)
-> (Last a -> String) -> ([Last a] -> ShowS) -> Show (Last a)
forall a. Show a => Int -> Last a -> ShowS
forall a. Show a => [Last a] -> ShowS
forall a. Show a => Last a -> String
forall a.
(Int -> a -> ShowS) -> (a -> String) -> ([a] -> ShowS) -> Show a
$cshowsPrec :: forall a. Show a => Int -> Last a -> ShowS
showsPrec :: Int -> Last a -> ShowS
$cshow :: forall a. Show a => Last a -> String
show :: Last a -> String
$cshowList :: forall a. Show a => [Last a] -> ShowS
showList :: [Last a] -> ShowS
Show -- ^ @since base-2.01,(forall x. Last a -> Rep (Last a) x)
-> (forall x. Rep (Last a) x -> Last a) -> Generic (Last a)
forall x. Rep (Last a) x -> Last a
forall x. Last a -> Rep (Last a) x
forall a.
(forall x. a -> Rep a x) -> (forall x. Rep a x -> a) -> Generic a
forall a x. Rep (Last a) x -> Last a
forall a x. Last a -> Rep (Last a) x
$cfrom :: forall a x. Last a -> Rep (Last a) x
from :: forall x. Last a -> Rep (Last a) x
$cto :: forall a x. Rep (Last a) x -> Last a
to :: forall x. Rep (Last a) x -> Last a
Generic -- ^ @since base-4.7.0.0,(forall a. Last a -> Rep1 Last a)
-> (forall a. Rep1 Last a -> Last a) -> Generic1 Last
forall a. Rep1 Last a -> Last a
forall a. Last a -> Rep1 Last a
forall k (f :: k -> *).
(forall (a :: k). f a -> Rep1 f a)
-> (forall (a :: k). Rep1 f a -> f a) -> Generic1 f
$cfrom1 :: forall a. Last a -> Rep1 Last a
from1 :: forall a. Last a -> Rep1 Last a
$cto1 :: forall a. Rep1 Last a -> Last a
to1 :: forall a. Rep1 Last a -> Last a
Generic1 -- ^ @since base-4.7.0.0,(forall a b. (a -> b) -> Last a -> Last b)
-> (forall a b. a -> Last b -> Last a) -> Functor Last
forall a b. a -> Last b -> Last a
forall a b. (a -> b) -> Last a -> Last b
forall (f :: * -> *).
(forall a b. (a -> b) -> f a -> f b)
-> (forall a b. a -> f b -> f a) -> Functor f
$cfmap :: forall a b. (a -> b) -> Last a -> Last b
fmap :: forall a b. (a -> b) -> Last a -> Last b
$c<$ :: forall a b. a -> Last b -> Last a
<$ :: forall a b. a -> Last b -> Last a
Functor -- ^ @since base-4.8.0.0,Functor Last
Functor Last =>
(forall a. a -> Last a)
-> (forall a b. Last (a -> b) -> Last a -> Last b)
-> (forall a b c. (a -> b -> c) -> Last a -> Last b -> Last c)
-> (forall a b. Last a -> Last b -> Last b)
-> (forall a b. Last a -> Last b -> Last a)
-> Applicative Last
forall a. a -> Last a
forall a b. Last a -> Last b -> Last a
forall a b. Last a -> Last b -> Last b
forall a b. Last (a -> b) -> Last a -> Last b
forall a b c. (a -> b -> c) -> Last a -> Last b -> Last c
forall (f :: * -> *).
Functor f =>
(forall a. a -> f a)
-> (forall a b. f (a -> b) -> f a -> f b)
-> (forall a b c. (a -> b -> c) -> f a -> f b -> f c)
-> (forall a b. f a -> f b -> f b)
-> (forall a b. f a -> f b -> f a)
-> Applicative f
$cpure :: forall a. a -> Last a
pure :: forall a. a -> Last a
$c<*> :: forall a b. Last (a -> b) -> Last a -> Last b
<*> :: forall a b. Last (a -> b) -> Last a -> Last b
$cliftA2 :: forall a b c. (a -> b -> c) -> Last a -> Last b -> Last c
liftA2 :: forall a b c. (a -> b -> c) -> Last a -> Last b -> Last c
$c*> :: forall a b. Last a -> Last b -> Last b
*> :: forall a b. Last a -> Last b -> Last b
$c<* :: forall a b. Last a -> Last b -> Last a
<* :: forall a b. Last a -> Last b -> Last a
Applicative -- ^ @since base-4.8.0.0,Applicative Last
Applicative Last =>
(forall a b. Last a -> (a -> Last b) -> Last b)
-> (forall a b. Last a -> Last b -> Last b)
-> (forall a. a -> Last a)
-> Monad Last
forall a. a -> Last a
forall a b. Last a -> Last b -> Last b
forall a b. Last a -> (a -> Last b) -> Last b
forall (m :: * -> *).
Applicative m =>
(forall a b. m a -> (a -> m b) -> m b)
-> (forall a b. m a -> m b -> m b)
-> (forall a. a -> m a)
-> Monad m
$c>>= :: forall a b. Last a -> (a -> Last b) -> Last b
>>= :: forall a b. Last a -> (a -> Last b) -> Last b
$c>> :: forall a b. Last a -> Last b -> Last b
>> :: forall a b. Last a -> Last b -> Last b
$creturn :: forall a. a -> Last a
return :: forall a. a -> Last a
Monad -- ^ @since base-4.8.0.0)-- | @since base-4.9.0.0instanceSemigroup (Last a )whereLast a
a <> :: Last a -> Last a -> Last a
<> Last Maybe a
Nothing =Last a
a Last a
_<> Last a
b =Last a
b stimes :: forall b. Integral b => b -> Last a -> Last a
stimes =b -> Last a -> Last a
forall b a. (Integral b, Monoid a) => b -> a -> a
stimesIdempotentMonoid -- | @since base-2.01instanceMonoid (Last a )wheremempty :: Last a
mempty =Maybe a -> Last a
forall a. Maybe a -> Last a
Last Maybe a
forall a. Maybe a
Nothing -- | This data type witnesses the lifting of a 'Monoid' into an-- 'Applicative' pointwise.---- ==== __Examples__---- >>> Ap (Just [1, 2, 3]) <> Ap Nothing-- Ap {getAp = Nothing}---- >>> Ap [Sum 10, Sum 20] <> Ap [Sum 1, Sum 2]-- Ap {getAp = [Sum {getSum = 11},Sum {getSum = 12},Sum {getSum = 21},Sum {getSum = 22}]}---- @since base-4.12.0.0newtypeAp f a =Ap {forall {k} (f :: k -> *) (a :: k). Ap f a -> f a
getAp ::f a }deriving(Applicative (Ap f)
Applicative (Ap f) =>
(forall a. Ap f a)
-> (forall a. Ap f a -> Ap f a -> Ap f a)
-> (forall a. Ap f a -> Ap f [a])
-> (forall a. Ap f a -> Ap f [a])
-> Alternative (Ap f)
forall a. Ap f a
forall a. Ap f a -> Ap f [a]
forall a. Ap f a -> Ap f a -> Ap f a
forall (f :: * -> *).
Applicative f =>
(forall a. f a)
-> (forall a. f a -> f a -> f a)
-> (forall a. f a -> f [a])
-> (forall a. f a -> f [a])
-> Alternative f
forall (f :: * -> *). Alternative f => Applicative (Ap f)
forall (f :: * -> *) a. Alternative f => Ap f a
forall (f :: * -> *) a. Alternative f => Ap f a -> Ap f [a]
forall (f :: * -> *) a. Alternative f => Ap f a -> Ap f a -> Ap f a
$cempty :: forall (f :: * -> *) a. Alternative f => Ap f a
empty :: forall a. Ap f a
$c<|> :: forall (f :: * -> *) a. Alternative f => Ap f a -> Ap f a -> Ap f a
<|> :: forall a. Ap f a -> Ap f a -> Ap f a
$csome :: forall (f :: * -> *) a. Alternative f => Ap f a -> Ap f [a]
some :: forall a. Ap f a -> Ap f [a]
$cmany :: forall (f :: * -> *) a. Alternative f => Ap f a -> Ap f [a]
many :: forall a. Ap f a -> Ap f [a]
Alternative -- ^ @since base-4.12.0.0,Functor (Ap f)
Functor (Ap f) =>
(forall a. a -> Ap f a)
-> (forall a b. Ap f (a -> b) -> Ap f a -> Ap f b)
-> (forall a b c. (a -> b -> c) -> Ap f a -> Ap f b -> Ap f c)
-> (forall a b. Ap f a -> Ap f b -> Ap f b)
-> (forall a b. Ap f a -> Ap f b -> Ap f a)
-> Applicative (Ap f)
forall a. a -> Ap f a
forall a b. Ap f a -> Ap f b -> Ap f a
forall a b. Ap f a -> Ap f b -> Ap f b
forall a b. Ap f (a -> b) -> Ap f a -> Ap f b
forall a b c. (a -> b -> c) -> Ap f a -> Ap f b -> Ap f c
forall (f :: * -> *).
Functor f =>
(forall a. a -> f a)
-> (forall a b. f (a -> b) -> f a -> f b)
-> (forall a b c. (a -> b -> c) -> f a -> f b -> f c)
-> (forall a b. f a -> f b -> f b)
-> (forall a b. f a -> f b -> f a)
-> Applicative f
forall (f :: * -> *). Applicative f => Functor (Ap f)
forall (f :: * -> *) a. Applicative f => a -> Ap f a
forall (f :: * -> *) a b.
Applicative f =>
Ap f a -> Ap f b -> Ap f a
forall (f :: * -> *) a b.
Applicative f =>
Ap f a -> Ap f b -> Ap f b
forall (f :: * -> *) a b.
Applicative f =>
Ap f (a -> b) -> Ap f a -> Ap f b
forall (f :: * -> *) a b c.
Applicative f =>
(a -> b -> c) -> Ap f a -> Ap f b -> Ap f c
$cpure :: forall (f :: * -> *) a. Applicative f => a -> Ap f a
pure :: forall a. a -> Ap f a
$c<*> :: forall (f :: * -> *) a b.
Applicative f =>
Ap f (a -> b) -> Ap f a -> Ap f b
<*> :: forall a b. Ap f (a -> b) -> Ap f a -> Ap f b
$cliftA2 :: forall (f :: * -> *) a b c.
Applicative f =>
(a -> b -> c) -> Ap f a -> Ap f b -> Ap f c
liftA2 :: forall a b c. (a -> b -> c) -> Ap f a -> Ap f b -> Ap f c
$c*> :: forall (f :: * -> *) a b.
Applicative f =>
Ap f a -> Ap f b -> Ap f b
*> :: forall a b. Ap f a -> Ap f b -> Ap f b
$c<* :: forall (f :: * -> *) a b.
Applicative f =>
Ap f a -> Ap f b -> Ap f a
<* :: forall a b. Ap f a -> Ap f b -> Ap f a
Applicative -- ^ @since base-4.12.0.0,Int -> Ap f a
Ap f a -> Int
Ap f a -> [Ap f a]
Ap f a -> Ap f a
Ap f a -> Ap f a -> [Ap f a]
Ap f a -> Ap f a -> Ap f a -> [Ap f a]
(Ap f a -> Ap f a)
-> (Ap f a -> Ap f a)
-> (Int -> Ap f a)
-> (Ap f a -> Int)
-> (Ap f a -> [Ap f a])
-> (Ap f a -> Ap f a -> [Ap f a])
-> (Ap f a -> Ap f a -> [Ap f a])
-> (Ap f a -> Ap f a -> Ap f a -> [Ap f a])
-> Enum (Ap f a)
forall a.
(a -> a)
-> (a -> a)
-> (Int -> a)
-> (a -> Int)
-> (a -> [a])
-> (a -> a -> [a])
-> (a -> a -> [a])
-> (a -> a -> a -> [a])
-> Enum a
forall k (f :: k -> *) (a :: k). Enum (f a) => Int -> Ap f a
forall k (f :: k -> *) (a :: k). Enum (f a) => Ap f a -> Int
forall k (f :: k -> *) (a :: k). Enum (f a) => Ap f a -> [Ap f a]
forall k (f :: k -> *) (a :: k). Enum (f a) => Ap f a -> Ap f a
forall k (f :: k -> *) (a :: k).
Enum (f a) =>
Ap f a -> Ap f a -> [Ap f a]
forall k (f :: k -> *) (a :: k).
Enum (f a) =>
Ap f a -> Ap f a -> Ap f a -> [Ap f a]
$csucc :: forall k (f :: k -> *) (a :: k). Enum (f a) => Ap f a -> Ap f a
succ :: Ap f a -> Ap f a
$cpred :: forall k (f :: k -> *) (a :: k). Enum (f a) => Ap f a -> Ap f a
pred :: Ap f a -> Ap f a
$ctoEnum :: forall k (f :: k -> *) (a :: k). Enum (f a) => Int -> Ap f a
toEnum :: Int -> Ap f a
$cfromEnum :: forall k (f :: k -> *) (a :: k). Enum (f a) => Ap f a -> Int
fromEnum :: Ap f a -> Int
$cenumFrom :: forall k (f :: k -> *) (a :: k). Enum (f a) => Ap f a -> [Ap f a]
enumFrom :: Ap f a -> [Ap f a]
$cenumFromThen :: forall k (f :: k -> *) (a :: k).
Enum (f a) =>
Ap f a -> Ap f a -> [Ap f a]
enumFromThen :: Ap f a -> Ap f a -> [Ap f a]
$cenumFromTo :: forall k (f :: k -> *) (a :: k).
Enum (f a) =>
Ap f a -> Ap f a -> [Ap f a]
enumFromTo :: Ap f a -> Ap f a -> [Ap f a]
$cenumFromThenTo :: forall k (f :: k -> *) (a :: k).
Enum (f a) =>
Ap f a -> Ap f a -> Ap f a -> [Ap f a]
enumFromThenTo :: Ap f a -> Ap f a -> Ap f a -> [Ap f a]
Enum -- ^ @since base-4.12.0.0,Ap f a -> Ap f a -> Bool
(Ap f a -> Ap f a -> Bool)
-> (Ap f a -> Ap f a -> Bool) -> Eq (Ap f a)
forall a. (a -> a -> Bool) -> (a -> a -> Bool) -> Eq a
forall k (f :: k -> *) (a :: k).
Eq (f a) =>
Ap f a -> Ap f a -> Bool
$c== :: forall k (f :: k -> *) (a :: k).
Eq (f a) =>
Ap f a -> Ap f a -> Bool
== :: Ap f a -> Ap f a -> Bool
$c/= :: forall k (f :: k -> *) (a :: k).
Eq (f a) =>
Ap f a -> Ap f a -> Bool
/= :: Ap f a -> Ap f a -> Bool
Eq -- ^ @since base-4.12.0.0,(forall a b. (a -> b) -> Ap f a -> Ap f b)
-> (forall a b. a -> Ap f b -> Ap f a) -> Functor (Ap f)
forall a b. a -> Ap f b -> Ap f a
forall a b. (a -> b) -> Ap f a -> Ap f b
forall (f :: * -> *) a b. Functor f => a -> Ap f b -> Ap f a
forall (f :: * -> *) a b. Functor f => (a -> b) -> Ap f a -> Ap f b
forall (f :: * -> *).
(forall a b. (a -> b) -> f a -> f b)
-> (forall a b. a -> f b -> f a) -> Functor f
$cfmap :: forall (f :: * -> *) a b. Functor f => (a -> b) -> Ap f a -> Ap f b
fmap :: forall a b. (a -> b) -> Ap f a -> Ap f b
$c<$ :: forall (f :: * -> *) a b. Functor f => a -> Ap f b -> Ap f a
<$ :: forall a b. a -> Ap f b -> Ap f a
Functor -- ^ @since base-4.12.0.0,(forall x. Ap f a -> Rep (Ap f a) x)
-> (forall x. Rep (Ap f a) x -> Ap f a) -> Generic (Ap f a)
forall x. Rep (Ap f a) x -> Ap f a
forall x. Ap f a -> Rep (Ap f a) x
forall a.
(forall x. a -> Rep a x) -> (forall x. Rep a x -> a) -> Generic a
forall k (f :: k -> *) (a :: k) x. Rep (Ap f a) x -> Ap f a
forall k (f :: k -> *) (a :: k) x. Ap f a -> Rep (Ap f a) x
$cfrom :: forall k (f :: k -> *) (a :: k) x. Ap f a -> Rep (Ap f a) x
from :: forall x. Ap f a -> Rep (Ap f a) x
$cto :: forall k (f :: k -> *) (a :: k) x. Rep (Ap f a) x -> Ap f a
to :: forall x. Rep (Ap f a) x -> Ap f a
Generic -- ^ @since base-4.12.0.0,(forall (a :: k). Ap f a -> Rep1 (Ap f) a)
-> (forall (a :: k). Rep1 (Ap f) a -> Ap f a) -> Generic1 (Ap f)
forall (a :: k). Rep1 (Ap f) a -> Ap f a
forall (a :: k). Ap f a -> Rep1 (Ap f) a
forall k (f :: k -> *).
(forall (a :: k). f a -> Rep1 f a)
-> (forall (a :: k). Rep1 f a -> f a) -> Generic1 f
forall k (f :: k -> *) (a :: k). Rep1 (Ap f) a -> Ap f a
forall k (f :: k -> *) (a :: k). Ap f a -> Rep1 (Ap f) a
$cfrom1 :: forall k (f :: k -> *) (a :: k). Ap f a -> Rep1 (Ap f) a
from1 :: forall (a :: k). Ap f a -> Rep1 (Ap f) a
$cto1 :: forall k (f :: k -> *) (a :: k). Rep1 (Ap f) a -> Ap f a
to1 :: forall (a :: k). Rep1 (Ap f) a -> Ap f a
Generic1 -- ^ @since base-4.12.0.0,Applicative (Ap f)
Applicative (Ap f) =>
(forall a b. Ap f a -> (a -> Ap f b) -> Ap f b)
-> (forall a b. Ap f a -> Ap f b -> Ap f b)
-> (forall a. a -> Ap f a)
-> Monad (Ap f)
forall a. a -> Ap f a
forall a b. Ap f a -> Ap f b -> Ap f b
forall a b. Ap f a -> (a -> Ap f b) -> Ap f b
forall (f :: * -> *). Monad f => Applicative (Ap f)
forall (f :: * -> *) a. Monad f => a -> Ap f a
forall (f :: * -> *) a b. Monad f => Ap f a -> Ap f b -> Ap f b
forall (f :: * -> *) a b.
Monad f =>
Ap f a -> (a -> Ap f b) -> Ap f b
forall (m :: * -> *).
Applicative m =>
(forall a b. m a -> (a -> m b) -> m b)
-> (forall a b. m a -> m b -> m b)
-> (forall a. a -> m a)
-> Monad m
$c>>= :: forall (f :: * -> *) a b.
Monad f =>
Ap f a -> (a -> Ap f b) -> Ap f b
>>= :: forall a b. Ap f a -> (a -> Ap f b) -> Ap f b
$c>> :: forall (f :: * -> *) a b. Monad f => Ap f a -> Ap f b -> Ap f b
>> :: forall a b. Ap f a -> Ap f b -> Ap f b
$creturn :: forall (f :: * -> *) a. Monad f => a -> Ap f a
return :: forall a. a -> Ap f a
Monad -- ^ @since base-4.12.0.0,Monad (Ap f)
Monad (Ap f) => (forall a. String -> Ap f a) -> MonadFail (Ap f)
forall a. String -> Ap f a
forall (m :: * -> *).
Monad m =>
(forall a. String -> m a) -> MonadFail m
forall (f :: * -> *). MonadFail f => Monad (Ap f)
forall (f :: * -> *) a. MonadFail f => String -> Ap f a
$cfail :: forall (f :: * -> *) a. MonadFail f => String -> Ap f a
fail :: forall a. String -> Ap f a
MonadFail -- ^ @since base-4.12.0.0,Monad (Ap f)
Alternative (Ap f)
(Alternative (Ap f), Monad (Ap f)) =>
(forall a. Ap f a)
-> (forall a. Ap f a -> Ap f a -> Ap f a) -> MonadPlus (Ap f)
forall a. Ap f a
forall a. Ap f a -> Ap f a -> Ap f a
forall (f :: * -> *). MonadPlus f => Monad (Ap f)
forall (f :: * -> *). MonadPlus f => Alternative (Ap f)
forall (f :: * -> *) a. MonadPlus f => Ap f a
forall (f :: * -> *) a. MonadPlus f => Ap f a -> Ap f a -> Ap f a
forall (m :: * -> *).
(Alternative m, Monad m) =>
(forall a. m a) -> (forall a. m a -> m a -> m a) -> MonadPlus m
$cmzero :: forall (f :: * -> *) a. MonadPlus f => Ap f a
mzero :: forall a. Ap f a
$cmplus :: forall (f :: * -> *) a. MonadPlus f => Ap f a -> Ap f a -> Ap f a
mplus :: forall a. Ap f a -> Ap f a -> Ap f a
MonadPlus -- ^ @since base-4.12.0.0,Eq (Ap f a)
Eq (Ap f a) =>
(Ap f a -> Ap f a -> Ordering)
-> (Ap f a -> Ap f a -> Bool)
-> (Ap f a -> Ap f a -> Bool)
-> (Ap f a -> Ap f a -> Bool)
-> (Ap f a -> Ap f a -> Bool)
-> (Ap f a -> Ap f a -> Ap f a)
-> (Ap f a -> Ap f a -> Ap f a)
-> Ord (Ap f a)
Ap f a -> Ap f a -> Bool
Ap f a -> Ap f a -> Ordering
Ap f a -> Ap f a -> Ap f a
forall a.
Eq a =>
(a -> a -> Ordering)
-> (a -> a -> Bool)
-> (a -> a -> Bool)
-> (a -> a -> Bool)
-> (a -> a -> Bool)
-> (a -> a -> a)
-> (a -> a -> a)
-> Ord a
forall k (f :: k -> *) (a :: k). Ord (f a) => Eq (Ap f a)
forall k (f :: k -> *) (a :: k).
Ord (f a) =>
Ap f a -> Ap f a -> Bool
forall k (f :: k -> *) (a :: k).
Ord (f a) =>
Ap f a -> Ap f a -> Ordering
forall k (f :: k -> *) (a :: k).
Ord (f a) =>
Ap f a -> Ap f a -> Ap f a
$ccompare :: forall k (f :: k -> *) (a :: k).
Ord (f a) =>
Ap f a -> Ap f a -> Ordering
compare :: Ap f a -> Ap f a -> Ordering
$c< :: forall k (f :: k -> *) (a :: k).
Ord (f a) =>
Ap f a -> Ap f a -> Bool
< :: Ap f a -> Ap f a -> Bool
$c<= :: forall k (f :: k -> *) (a :: k).
Ord (f a) =>
Ap f a -> Ap f a -> Bool
<= :: Ap f a -> Ap f a -> Bool
$c> :: forall k (f :: k -> *) (a :: k).
Ord (f a) =>
Ap f a -> Ap f a -> Bool
> :: Ap f a -> Ap f a -> Bool
$c>= :: forall k (f :: k -> *) (a :: k).
Ord (f a) =>
Ap f a -> Ap f a -> Bool
>= :: Ap f a -> Ap f a -> Bool
$cmax :: forall k (f :: k -> *) (a :: k).
Ord (f a) =>
Ap f a -> Ap f a -> Ap f a
max :: Ap f a -> Ap f a -> Ap f a
$cmin :: forall k (f :: k -> *) (a :: k).
Ord (f a) =>
Ap f a -> Ap f a -> Ap f a
min :: Ap f a -> Ap f a -> Ap f a
Ord -- ^ @since base-4.12.0.0,ReadPrec [Ap f a]
ReadPrec (Ap f a)
Int -> ReadS (Ap f a)
ReadS [Ap f a]
(Int -> ReadS (Ap f a))
-> ReadS [Ap f a]
-> ReadPrec (Ap f a)
-> ReadPrec [Ap f a]
-> Read (Ap f a)
forall a.
(Int -> ReadS a)
-> ReadS [a] -> ReadPrec a -> ReadPrec [a] -> Read a
forall k (f :: k -> *) (a :: k). Read (f a) => ReadPrec [Ap f a]
forall k (f :: k -> *) (a :: k). Read (f a) => ReadPrec (Ap f a)
forall k (f :: k -> *) (a :: k).
Read (f a) =>
Int -> ReadS (Ap f a)
forall k (f :: k -> *) (a :: k). Read (f a) => ReadS [Ap f a]
$creadsPrec :: forall k (f :: k -> *) (a :: k).
Read (f a) =>
Int -> ReadS (Ap f a)
readsPrec :: Int -> ReadS (Ap f a)
$creadList :: forall k (f :: k -> *) (a :: k). Read (f a) => ReadS [Ap f a]
readList :: ReadS [Ap f a]
$creadPrec :: forall k (f :: k -> *) (a :: k). Read (f a) => ReadPrec (Ap f a)
readPrec :: ReadPrec (Ap f a)
$creadListPrec :: forall k (f :: k -> *) (a :: k). Read (f a) => ReadPrec [Ap f a]
readListPrec :: ReadPrec [Ap f a]
Read -- ^ @since base-4.12.0.0,Int -> Ap f a -> ShowS
[Ap f a] -> ShowS
Ap f a -> String
(Int -> Ap f a -> ShowS)
-> (Ap f a -> String) -> ([Ap f a] -> ShowS) -> Show (Ap f a)
forall a.
(Int -> a -> ShowS) -> (a -> String) -> ([a] -> ShowS) -> Show a
forall k (f :: k -> *) (a :: k).
Show (f a) =>
Int -> Ap f a -> ShowS
forall k (f :: k -> *) (a :: k). Show (f a) => [Ap f a] -> ShowS
forall k (f :: k -> *) (a :: k). Show (f a) => Ap f a -> String
$cshowsPrec :: forall k (f :: k -> *) (a :: k).
Show (f a) =>
Int -> Ap f a -> ShowS
showsPrec :: Int -> Ap f a -> ShowS
$cshow :: forall k (f :: k -> *) (a :: k). Show (f a) => Ap f a -> String
show :: Ap f a -> String
$cshowList :: forall k (f :: k -> *) (a :: k). Show (f a) => [Ap f a] -> ShowS
showList :: [Ap f a] -> ShowS
Show -- ^ @since base-4.12.0.0)-- | @since base-4.12.0.0instance(Applicative f ,Semigroup a )=>Semigroup (Ap f a )where(Ap f a
x )<> :: Ap f a -> Ap f a -> Ap f a
<> (Ap f a
y )=f a -> Ap f a
forall {k} (f :: k -> *) (a :: k). f a -> Ap f a
Ap (f a -> Ap f a) -> f a -> Ap f a
forall a b. (a -> b) -> a -> b
$ (a -> a -> a) -> f a -> f a -> f a
forall a b c. (a -> b -> c) -> f a -> f b -> f c
forall (f :: * -> *) a b c.
Applicative f =>
(a -> b -> c) -> f a -> f b -> f c
liftA2 a -> a -> a
forall a. Semigroup a => a -> a -> a
(<>) f a
x f a
y -- | @since base-4.12.0.0instance(Applicative f ,Monoid a )=>Monoid (Ap f a )wheremempty :: Ap f a
mempty =f a -> Ap f a
forall {k} (f :: k -> *) (a :: k). f a -> Ap f a
Ap (f a -> Ap f a) -> f a -> Ap f a
forall a b. (a -> b) -> a -> b
$ a -> f a
forall a. a -> f a
forall (f :: * -> *) a. Applicative f => a -> f a
pure a
forall a. Monoid a => a
mempty -- | @since base-4.12.0.0instance(Applicative f ,Bounded a )=>Bounded (Ap f a )whereminBound :: Ap f a
minBound =a -> Ap f a
forall a. a -> Ap f a
forall (f :: * -> *) a. Applicative f => a -> f a
pure a
forall a. Bounded a => a
minBound maxBound :: Ap f a
maxBound =a -> Ap f a
forall a. a -> Ap f a
forall (f :: * -> *) a. Applicative f => a -> f a
pure a
forall a. Bounded a => a
maxBound -- | Note that even if the underlying 'Num' and 'Applicative' instances are-- lawful, for most 'Applicative's, this instance will not be lawful. If you use-- this instance with the list 'Applicative', the following customary laws will-- not hold:---- Commutativity:---- >>> Ap [10,20] + Ap [1,2]-- Ap {getAp = [11,12,21,22]}-- >>> Ap [1,2] + Ap [10,20]-- Ap {getAp = [11,21,12,22]}---- Additive inverse:---- >>> Ap [] + negate (Ap [])-- Ap {getAp = []}-- >>> fromInteger 0 :: Ap [] Int-- Ap {getAp = [0]}---- Distributivity:---- >>> Ap [1,2] * (3 + 4)-- Ap {getAp = [7,14]}-- >>> (Ap [1,2] * 3) + (Ap [1,2] * 4)-- Ap {getAp = [7,11,10,14]}---- @since base-4.12.0.0instance(Applicative f ,Num a )=>Num (Ap f a )where+ :: Ap f a -> Ap f a -> Ap f a
(+) =(a -> a -> a) -> Ap f a -> Ap f a -> Ap f a
forall a b c. (a -> b -> c) -> Ap f a -> Ap f b -> Ap f c
forall (f :: * -> *) a b c.
Applicative f =>
(a -> b -> c) -> f a -> f b -> f c
liftA2 a -> a -> a
forall a. Num a => a -> a -> a
(+) * :: Ap f a -> Ap f a -> Ap f a
(*) =(a -> a -> a) -> Ap f a -> Ap f a -> Ap f a
forall a b c. (a -> b -> c) -> Ap f a -> Ap f b -> Ap f c
forall (f :: * -> *) a b c.
Applicative f =>
(a -> b -> c) -> f a -> f b -> f c
liftA2 a -> a -> a
forall a. Num a => a -> a -> a
(*) negate :: Ap f a -> Ap f a
negate =(a -> a) -> Ap f a -> Ap f a
forall a b. (a -> b) -> Ap f a -> Ap f b
forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
fmap a -> a
forall a. Num a => a -> a
negate fromInteger :: Integer -> Ap f a
fromInteger =a -> Ap f a
forall a. a -> Ap f a
forall (f :: * -> *) a. Applicative f => a -> f a
pure (a -> Ap f a) -> (Integer -> a) -> Integer -> Ap f a
forall b c a. (b -> c) -> (a -> b) -> a -> c
. Integer -> a
forall a. Num a => Integer -> a
fromInteger abs :: Ap f a -> Ap f a
abs =(a -> a) -> Ap f a -> Ap f a
forall a b. (a -> b) -> Ap f a -> Ap f b
forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
fmap a -> a
forall a. Num a => a -> a
abs signum :: Ap f a -> Ap f a
signum =(a -> a) -> Ap f a -> Ap f a
forall a b. (a -> b) -> Ap f a -> Ap f b
forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
fmap a -> a
forall a. Num a => a -> a
signum {-
{--------------------------------------------------------------------
 Testing
--------------------------------------------------------------------}
instance Arbitrary a => Arbitrary (Maybe a) where
 arbitrary = oneof [return Nothing, Just `fmap` arbitrary]
prop_mconcatMaybe :: [Maybe [Int]] -> Bool
prop_mconcatMaybe x =
 fromMaybe [] (mconcat x) == mconcat (catMaybes x)
prop_mconcatFirst :: [Maybe Int] -> Bool
prop_mconcatFirst x =
 getFirst (mconcat (map First x)) == listToMaybe (catMaybes x)
prop_mconcatLast :: [Maybe Int] -> Bool
prop_mconcatLast x =
 getLast (mconcat (map Last x)) == listLastToMaybe (catMaybes x)
 where listLastToMaybe [] = Nothing
 listLastToMaybe lst = Just (last lst)
-- -}