Safe Haskell	None
Language	Haskell98

Language.Haskell.TH.FlexibleDefaults

Description

A code-generation system for complex typeclass default-implementation configurations. There are usage examples in this package's source distribution[1] and in the random-source package[2].

Synopsis

data Defaults s a
scoreBy :: (a -> b) -> Defaults a t -> Defaults b t
data Function s a
function :: String -> Function s a -> Defaults s a
requireFunction :: String -> Defaults s ()
data Implementation s a
implementation :: Implementation s (Q [Dec]) -> Function s ()
score :: s -> Implementation s ()
cost :: Num s => s -> Implementation s ()
dependsOn :: String -> Implementation s ()
inline :: Implementation s ()
noinline :: Implementation s ()
withDefaults :: (Monoid s, Ord s) => Defaults s () -> Q [Dec] -> Q [Dec]
implementDefaults :: (Ord s, Monoid s) => Defaults s () -> [Dec] -> Q [Dec]

Documentation

data Defaults s a Source #

A description of a system of Functions and default Implementations which can be used to complete a partial implementation of some type class.

Instances

Instances details

Monad (Defaults s) Source #
Instance details Defined in Language.Haskell.TH.FlexibleDefaults.DSL Methods (>>=) :: Defaults s a -> (a -> Defaults s b) -> Defaults s b (>>) :: Defaults s a -> Defaults s b -> Defaults s b return :: a -> Defaults s a
Functor (Defaults s) Source #
Instance details Defined in Language.Haskell.TH.FlexibleDefaults.DSL Methods fmap :: (a -> b) -> Defaults s a -> Defaults s b (<$) :: a -> Defaults s b -> Defaults s a
Applicative (Defaults s) Source #
Instance details Defined in Language.Haskell.TH.FlexibleDefaults.DSL Methods pure :: a -> Defaults s a (<>) :: Defaults s (a -> b) -> Defaults s a -> Defaults s b liftA2 :: (a -> b -> c) -> Defaults s a -> Defaults s b -> Defaults s c (>) :: Defaults s a -> Defaults s b -> Defaults s b (<*) :: Defaults s a -> Defaults s b -> Defaults s a

scoreBy :: (a -> b) -> Defaults a t -> Defaults b t Source #

Map a function over all scores. This function's name comes from the following idiom (where Sum is replaced by whatever monoid-constructor you want to use to combine scores):

foo = scoreBy Sum $ do
   ...

data Function s a Source #

A representation of a function for which one or more default Implementations exist. Defined using the function function.

Instances

Instances details

Monad (Function s) Source #
Instance details Defined in Language.Haskell.TH.FlexibleDefaults.DSL Methods (>>=) :: Function s a -> (a -> Function s b) -> Function s b (>>) :: Function s a -> Function s b -> Function s b return :: a -> Function s a
Functor (Function s) Source #
Instance details Defined in Language.Haskell.TH.FlexibleDefaults.DSL Methods fmap :: (a -> b) -> Function s a -> Function s b (<$) :: a -> Function s b -> Function s a
Applicative (Function s) Source #
Instance details Defined in Language.Haskell.TH.FlexibleDefaults.DSL Methods pure :: a -> Function s a (<>) :: Function s (a -> b) -> Function s a -> Function s b liftA2 :: (a -> b -> c) -> Function s a -> Function s b -> Function s c (>) :: Function s a -> Function s b -> Function s b (<*) :: Function s a -> Function s b -> Function s a

function :: String -> Function s a -> Defaults s a Source #

Declare a function that must be implemented, and provide a description of any default implementations which can be used.

requireFunction :: String -> Defaults s () Source #

State that a function must be implemented but has no default implementation.

data Implementation s a Source #

A representation of a single possible implementation of a Function. Defined using the implementation function.

Instances

Instances details

Monad (Implementation s) Source #
Instance details Defined in Language.Haskell.TH.FlexibleDefaults.DSL Methods (>>=) :: Implementation s a -> (a -> Implementation s b) -> Implementation s b (>>) :: Implementation s a -> Implementation s b -> Implementation s b return :: a -> Implementation s a
Functor (Implementation s) Source #
Instance details Defined in Language.Haskell.TH.FlexibleDefaults.DSL Methods fmap :: (a -> b) -> Implementation s a -> Implementation s b (<$) :: a -> Implementation s b -> Implementation s a
Applicative (Implementation s) Source #
Instance details Defined in Language.Haskell.TH.FlexibleDefaults.DSL Methods pure :: a -> Implementation s a (<>) :: Implementation s (a -> b) -> Implementation s a -> Implementation s b liftA2 :: (a -> b -> c) -> Implementation s a -> Implementation s b -> Implementation s c (>) :: Implementation s a -> Implementation s b -> Implementation s b (<*) :: Implementation s a -> Implementation s b -> Implementation s a

implementation :: Implementation s (Q [Dec]) -> Function s () Source #

Describe a default implementation of the current function

score :: s -> Implementation s () Source #

Specify the score associated with the current implementation. Only one invocation of either score or cost may be used per implementation.

cost :: Num s => s -> Implementation s () Source #

Specify the cost (negated score) associated with the current implementation. Only one invocation of either score or cost may be used per implementation.

dependsOn :: String -> Implementation s () Source #

Specify that the current implementation must not be used unless the given function is already defined. If this implementation can be used mutually-recursively with _ALL_ potential implementations of some other function, then a dependency need not be declared on that function.

inline :: Implementation s () Source #

Specify that an Implementation should be annotated with an INLINE pragma. Under GHC versions earlier than 6.12 this is a no-op, because those Template Haskell implementations do not support pragmas.

noinline :: Implementation s () Source #

Specify that an Implementation should be annotated with a NOINLINE pragma. Under GHC versions earlier than 6.12 this is a no-op, because those Template Haskell implementations do not support pragmas.

withDefaults :: (Monoid s, Ord s) => Defaults s () -> Q [Dec] -> Q [Dec] Source #

Given a Q [Dec] containing an instance declaration, complete that instance declaration using the given Defaults specification. Typical usage would be along the lines of the following:

$(withDefaults fooDefaults [d| instance Foo t where {- ... -} |])

implementDefaults :: (Ord s, Monoid s) => Defaults s () -> [Dec] -> Q [Dec] Source #

Given a partial list of function declarations, complete that list based on the Defaults specification given.