Distribution.Simple.Flag

Defines the Flag type and it's Monoid instance, see http://www.haskell.org/pipermail/cabal-devel/2007-December/001509.html for an explanation.

Split off from Distribution.Simple.Setup to break import cycles.

Documentation

data Flag a

All flags are monoids, they come in two flavours:

1. list flags eg

--ghc-option=foo --ghc-option=bar

gives us all the values ["foo", "bar"]

2. singular value flags, eg:

--enable-foo --disable-foo

gives us Just False

So, this Flag type is for the latter singular kind of flag. Its monoid instance gives us the behaviour where it starts out as NoFlag and later flags override earlier ones.

Isomorphic to Maybe a.

Constructors

Flag a

NoFlag

Instances

Foldable Flag

Defined in Distribution.Simple.Flag

Methods

fold :: Monoid m => Flag m -> m

foldMap :: Monoid m => (a -> m) -> Flag a -> m

foldMap' :: Monoid m => (a -> m) -> Flag a -> m

foldr :: (a -> b -> b) -> b -> Flag a -> b

foldr' :: (a -> b -> b) -> b -> Flag a -> b

foldl :: (b -> a -> b) -> b -> Flag a -> b

foldl' :: (b -> a -> b) -> b -> Flag a -> b

foldr1 :: (a -> a -> a) -> Flag a -> a

foldl1 :: (a -> a -> a) -> Flag a -> a

toList :: Flag a -> [a]

null :: Flag a -> Bool

length :: Flag a -> Int

elem :: Eq a => a -> Flag a -> Bool

maximum :: Ord a => Flag a -> a

minimum :: Ord a => Flag a -> a

sum :: Num a => Flag a -> a

product :: Num a => Flag a -> a

Traversable Flag

Defined in Distribution.Simple.Flag

Methods

traverse :: Applicative f => (a -> f b) -> Flag a -> f (Flag b)

sequenceA :: Applicative f => Flag (f a) -> f (Flag a)

mapM :: Monad m => (a -> m b) -> Flag a -> m (Flag b)

sequence :: Monad m => Flag (m a) -> m (Flag a)

Applicative Flag

Defined in Distribution.Simple.Flag

Methods

pure :: a -> Flag a

(<*>) :: Flag (a -> b) -> Flag a -> Flag b

liftA2 :: (a -> b -> c) -> Flag a -> Flag b -> Flag c

(*>) :: Flag a -> Flag b -> Flag b

(<*) :: Flag a -> Flag b -> Flag a

Functor Flag

Defined in Distribution.Simple.Flag

Methods

fmap :: (a -> b) -> Flag a -> Flag b

(<$) :: a -> Flag b -> Flag a

Structured a => Structured (Flag a)

Defined in Distribution.Simple.Flag

Methods

structure :: Proxy (Flag a) -> Structure

structureHash' :: Tagged (Flag a) MD5

Monoid (Flag a)

Defined in Distribution.Simple.Flag

Methods

mempty :: Flag a

mappend :: Flag a -> Flag a -> Flag a

mconcat :: [Flag a] -> Flag a

Semigroup (Flag a)

Defined in Distribution.Simple.Flag

Methods

(<>) :: Flag a -> Flag a -> Flag a

sconcat :: NonEmpty (Flag a) -> Flag a

stimes :: Integral b => b -> Flag a -> Flag a

Bounded a => Bounded (Flag a)

Defined in Distribution.Simple.Flag

Methods

minBound :: Flag a

maxBound :: Flag a

Enum a => Enum (Flag a)

Defined in Distribution.Simple.Flag

Methods

succ :: Flag a -> Flag a

pred :: Flag a -> Flag a

toEnum :: Int -> Flag a

fromEnum :: Flag a -> Int

enumFrom :: Flag a -> [Flag a]

enumFromThen :: Flag a -> Flag a -> [Flag a]

enumFromTo :: Flag a -> Flag a -> [Flag a]

enumFromThenTo :: Flag a -> Flag a -> Flag a -> [Flag a]

Generic (Flag a)

Defined in Distribution.Simple.Flag

Associated Types

type Rep (Flag a) :: Type -> Type

Methods

from :: Flag a -> Rep (Flag a) x

to :: Rep (Flag a) x -> Flag a

Read a => Read (Flag a)

Defined in Distribution.Simple.Flag

Methods

readsPrec :: Int -> ReadS (Flag a)

readList :: ReadS [Flag a]

readPrec :: ReadPrec (Flag a)

readListPrec :: ReadPrec [Flag a]

Show a => Show (Flag a)

Defined in Distribution.Simple.Flag

Methods

showsPrec :: Int -> Flag a -> ShowS

show :: Flag a -> String

showList :: [Flag a] -> ShowS

Binary a => Binary (Flag a)

Defined in Distribution.Simple.Flag

Methods

put :: Flag a -> Put

get :: Get (Flag a)

putList :: [Flag a] -> Put

Eq a => Eq (Flag a)

Defined in Distribution.Simple.Flag

Methods

(==) :: Flag a -> Flag a -> Bool

(/=) :: Flag a -> Flag a -> Bool

type Rep (Flag a)

Defined in Distribution.Simple.Flag

type Rep (Flag a) = D1 ('MetaData "Flag" "Distribution.Simple.Flag" "Cabal-3.14.0.0-inplace" 'False) (C1 ('MetaCons "Flag" 'PrefixI 'False) (S1 ('MetaSel ('Nothing :: Maybe Symbol) 'NoSourceUnpackedness 'NoSourceStrictness 'DecidedLazy) (Rec0 a)) :+: C1 ('MetaCons "NoFlag" 'PrefixI 'False) (U1 :: Type -> Type))

allFlags :: [Flag Bool] -> Flag Bool

Returns True only if every Flag Bool value is Flag True, else False.

toFlag :: a -> Flag a

Wraps a value in Flag.

fromFlag :: WithCallStack (Flag a -> a)

Extracts a value from a Flag, and throws an exception on NoFlag.

fromFlagOrDefault :: a -> Flag a -> a

Extracts a value from a Flag, and returns the default value on NoFlag.

flagElim :: b -> (a -> b) -> Flag a -> b

Pushes a function through a Flag value, and returns a default if the Flag value is NoFlag.

Since: 3.4.0.0

flagToMaybe :: Flag a -> Maybe a

Converts a Flag value to a Maybe value.

flagToList :: Flag a -> [a]

Converts a Flag value to a list.

maybeToFlag :: Maybe a -> Flag a

Converts a Maybe value to a Flag value.

mergeListFlag :: Flag [a] -> Flag [a] -> Flag [a]

Merge the elements of a list Flag with another list Flag.

class BooleanFlag a where

Types that represent boolean flags.

Methods

asBool :: a -> Bool

Instances

BooleanFlag Bool

Defined in Distribution.Simple.Flag

Methods

asBool :: Bool -> Bool