Copyright	Isaac Jones 2003-2004 Duncan Coutts 2007
License	BSD3
Maintainer	cabal-devel@haskell.org
Portability	portable
Safe Haskell	None
Language	Haskell2010

Distribution.Simple.Flag

Description

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.

Synopsis

data Flag a
- = Flag a
- | NoFlag
allFlags :: [Flag Bool] -> Flag Bool
toFlag :: a -> Flag a
fromFlag :: WithCallStack (Flag a -> a)
fromFlagOrDefault :: a -> Flag a -> a
flagToMaybe :: Flag a -> Maybe a
flagToList :: Flag a -> [a]
maybeToFlag :: Maybe a -> Flag a
class BooleanFlag a where
- asBool :: a -> Bool

Documentation

data Flag a Source #

All flags are monoids, they come in two flavours:

list flags eg

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

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

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.

Constructors

Flag a
NoFlag

Instances

Instances details

Functor Flag Source #
Instance details Defined in Distribution.Simple.Flag Methods fmap :: (a -> b) -> Flag a -> Flag b Source # (<$) :: a -> Flag b -> Flag a Source #
Applicative Flag Source #
Instance details Defined in Distribution.Simple.Flag Methods pure :: a -> Flag a Source # (<>) :: Flag (a -> b) -> Flag a -> Flag b Source # liftA2 :: (a -> b -> c) -> Flag a -> Flag b -> Flag c Source # (>) :: Flag a -> Flag b -> Flag b Source # (<*) :: Flag a -> Flag b -> Flag a Source #
Bounded a => Bounded (Flag a) Source #
Instance details Defined in Distribution.Simple.Flag Methods minBound :: Flag a Source # maxBound :: Flag a Source #
Enum a => Enum (Flag a) Source #
Instance details Defined in Distribution.Simple.Flag Methods succ :: Flag a -> Flag a Source # pred :: Flag a -> Flag a Source # toEnum :: Int -> Flag a Source # fromEnum :: Flag a -> Int Source # enumFrom :: Flag a -> [Flag a] Source # enumFromThen :: Flag a -> Flag a -> [Flag a] Source # enumFromTo :: Flag a -> Flag a -> [Flag a] Source # enumFromThenTo :: Flag a -> Flag a -> Flag a -> [Flag a] Source #
Eq a => Eq (Flag a) Source #
Instance details Defined in Distribution.Simple.Flag Methods (==) :: Flag a -> Flag a -> Bool # (/=) :: Flag a -> Flag a -> Bool #
Read a => Read (Flag a) Source #
Instance details Defined in Distribution.Simple.Flag Methods readsPrec :: Int -> ReadS (Flag a) Source # readList :: ReadS [Flag a] Source # readPrec :: ReadPrec (Flag a) Source # readListPrec :: ReadPrec [Flag a] Source #
Show a => Show (Flag a) Source #
Instance details Defined in Distribution.Simple.Flag Methods showsPrec :: Int -> Flag a -> ShowS Source # show :: Flag a -> String Source # showList :: [Flag a] -> ShowS Source #
Generic (Flag a) Source #
Instance details Defined in Distribution.Simple.Flag Associated Types type Rep (Flag a) :: Type -> Type Source # Methods from :: Flag a -> Rep (Flag a) x Source # to :: Rep (Flag a) x -> Flag a Source #
Semigroup (Flag a) Source #
Instance details Defined in Distribution.Simple.Flag Methods (<>) :: Flag a -> Flag a -> Flag a Source # sconcat :: NonEmpty (Flag a) -> Flag a Source # stimes :: Integral b => b -> Flag a -> Flag a Source #
Monoid (Flag a) Source #
Instance details Defined in Distribution.Simple.Flag Methods mempty :: Flag a Source # mappend :: Flag a -> Flag a -> Flag a Source # mconcat :: [Flag a] -> Flag a Source #
Binary a => Binary (Flag a) Source #
Instance details Defined in Distribution.Simple.Flag Methods put :: Flag a -> Put Source # get :: Get (Flag a) Source # putList :: [Flag a] -> Put Source #
Structured a => Structured (Flag a) Source #
Instance details Defined in Distribution.Simple.Flag Methods structure :: Proxy (Flag a) -> Structure Source # structureHash' :: Tagged (Flag a) MD5
type Rep (Flag a) Source #
Instance details Defined in Distribution.Simple.Flag type Rep (Flag a) = D1 ('MetaData "Flag" "Distribution.Simple.Flag" "Cabal-3.2.0.0" '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 Source #

toFlag :: a -> Flag a Source #

fromFlag :: WithCallStack (Flag a -> a) Source #

fromFlagOrDefault :: a -> Flag a -> a Source #

flagToMaybe :: Flag a -> Maybe a Source #

flagToList :: Flag a -> [a] Source #

maybeToFlag :: Maybe a -> Flag a Source #

class BooleanFlag a where Source #

Types that represent boolean flags.

Methods

asBool :: a -> Bool Source #

Instances

Instances details

BooleanFlag Bool Source #
Instance details Defined in Distribution.Simple.Flag Methods asBool :: Bool -> Bool Source #