Data.Generics.Aliases

"Scrap your boilerplate" --- Generic programming in Haskell See http://www.cs.vu.nl/boilerplate/. The present module provides a number of declarations for typical generic function types, corresponding type case, and others.

Combinators to "make" generic functions via cast

mkT :: (Typeable a, Typeable b) => (b -> b) -> a -> a

Make a generic transformation; start from a type-specific case; preserve the term otherwise

mkQ :: (Typeable a, Typeable b) => r -> (b -> r) -> a -> r

Make a generic query; start from a type-specific case; return a constant otherwise

mkM :: (Monad m, Typeable a, Typeable b) => (b -> m b) -> a -> m a

Make a generic monadic transformation; start from a type-specific case; resort to return otherwise

mkMp :: (MonadPlus m, Typeable a, Typeable b) => (b -> m b) -> a -> m a

Make a generic monadic transformation for MonadPlus; use "const mzero" (i.e., failure) instead of return as default.

mkR :: (MonadPlus m, Typeable a, Typeable b) => m b -> m a

Make a generic builder; start from a type-specific ase; resort to no build (i.e., mzero) otherwise

ext0 :: (Typeable a, Typeable b) => c a -> c b -> c a

Flexible type extension

extT :: (Typeable a, Typeable b) => (a -> a) -> (b -> b) -> a -> a

Extend a generic transformation by a type-specific case

extQ :: (Typeable a, Typeable b) => (a -> q) -> (b -> q) -> a -> q

Extend a generic query by a type-specific case

extM :: (Monad m, Typeable a, Typeable b) => (a -> m a) -> (b -> m b) -> a -> m a

Extend a generic monadic transformation by a type-specific case

extMp :: (MonadPlus m, Typeable a, Typeable b) => (a -> m a) -> (b -> m b) -> a -> m a

Extend a generic MonadPlus transformation by a type-specific case

extB :: (Typeable a, Typeable b) => a -> b -> a

Extend a generic builder

extR :: (Monad m, Typeable a, Typeable b) => m a -> m b -> m a

Extend a generic reader

Type synonyms for generic function types

type GenericT = forall a. Data a => a -> a

Generic transformations, i.e., take an "a" and return an "a"

type GenericQ r = forall a. Data a => a -> r

Generic queries of type "r", i.e., take any "a" and return an "r"

type GenericM m = forall a. Data a => a -> m a

Generic monadic transformations, i.e., take an "a" and compute an "a"

type GenericB = forall a. Data a => a

Generic builders i.e., produce an "a".

type GenericR m = forall a. Data a => m a

Generic readers, say monadic builders, i.e., produce an "a" with the help of a monad "m".

type Generic c = forall a. Data a => a -> c a

The general scheme underlying generic functions assumed by gfoldl; there are isomorphisms such as GenericT = Generic T.

data Generic' c

Wrapped generic functions; recall: [Generic c] would be legal but [Generic' c] not.

Constructors

Generic'

Fields

unGeneric' :: Generic c

newtype GenericT'

Other first-class polymorphic wrappers

Constructors

GT

Fields

unGT :: forall a. Data a => a -> a

newtype GenericQ' r

Constructors

GQ

Fields

unGQ :: GenericQ r

newtype GenericM' m

Constructors

GM

Fields

unGM :: forall a. Data a => a -> m a

Ingredients of generic functions

orElse :: Maybe a -> Maybe a -> Maybe a

Left-biased choice on maybes

Function combinators on generic functions

recoverMp :: MonadPlus m => GenericM m -> GenericM m

Recover from the failure of monadic transformation by identity

recoverQ :: MonadPlus m => r -> GenericQ (m r) -> GenericQ (m r)

Recover from the failure of monadic query by a constant

choiceMp :: MonadPlus m => GenericM m -> GenericM m -> GenericM m

Choice for monadic transformations

choiceQ :: MonadPlus m => GenericQ (m r) -> GenericQ (m r) -> GenericQ (m r)

Choice for monadic queries

Type extension for unary type constructors

ext1T :: (Data d, Typeable1 t) => (forall e. Data e => e -> e) -> (forall f. Data f => t f -> t f) -> d -> d

Type extension of transformations for unary type constructors

ext1M :: (Monad m, Data d, Typeable1 t) => (forall e. Data e => e -> m e) -> (forall f. Data f => t f -> m (t f)) -> d -> m d

Type extension of monadic transformations for type constructors

ext1Q :: (Data d, Typeable1 t) => (d -> q) -> (forall e. Data e => t e -> q) -> d -> q

Type extension of queries for type constructors

ext1R :: (Monad m, Data d, Typeable1 t) => m d -> (forall e. Data e => m (t e)) -> m d

Type extension of readers for type constructors

ext1B :: (Data a, Typeable1 t) => a -> (forall b. Data b => t b) -> a

Type extension of builders for type constructors