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Data.Generics.Schemes

Portability | non-portable (local universal quantification)
Stability | experimental
Maintainer | libraries@haskell.org

Description
"Scrap your boilerplate" --- Generic programming in Haskell See http://www.cs.vu.nl/boilerplate/. The present module provides frequently used generic traversal schemes.
Synopsis

everywhere :: (forall a . Data a => a -> a) -> forall a . Data a => a -> a
everywhere' :: (forall a . Data a => a -> a) -> forall a . Data a => a -> a
everywhereBut :: GenericQ Bool -> GenericT -> GenericT
everywhereM :: Monad m => GenericM m -> GenericM m
somewhere :: MonadPlus m => GenericM m -> GenericM m
everything :: (r -> r -> r) -> GenericQ r -> GenericQ r
listify :: Typeable r => (r -> Bool) -> GenericQ [r]
something :: GenericQ (Maybe u) -> GenericQ (Maybe u)
synthesize :: s -> (s -> s -> s) -> GenericQ (s -> s) -> GenericQ s
gsize :: Data a => a -> Int
glength :: GenericQ Int
gdepth :: GenericQ Int
gcount :: GenericQ Bool -> GenericQ Int
gnodecount :: GenericQ Int
gtypecount :: Typeable a => a -> GenericQ Int
gfindtype :: (Data x, Typeable y) => x -> Maybe y

Documentation
everywhere :: (forall a . Data a => a -> a) -> forall a . Data a => a -> a
Apply a transformation everywhere in bottom-up manner
everywhere' :: (forall a . Data a => a -> a) -> forall a . Data a => a -> a
Apply a transformation everywhere in top-down manner
everywhereBut :: GenericQ Bool -> GenericT -> GenericT
Variation on everywhere with an extra stop condition
everywhereM :: Monad m => GenericM m -> GenericM m
Monadic variation on everywhere
somewhere :: MonadPlus m => GenericM m -> GenericM m
Apply a monadic transformation at least somewhere
everything :: (r -> r -> r) -> GenericQ r -> GenericQ r
Summarise all nodes in top-down, left-to-right order
listify :: Typeable r => (r -> Bool) -> GenericQ [r]
Get a list of all entities that meet a predicate
something :: GenericQ (Maybe u) -> GenericQ (Maybe u)
Look up a subterm by means of a maybe-typed filter
synthesize :: s -> (s -> s -> s) -> GenericQ (s -> s) -> GenericQ s
Bottom-up synthesis of a data structure; 1st argument z is the initial element for the synthesis; 2nd argument o is for reduction of results from subterms; 3rd argument f updates the synthesised data according to the given term
gsize :: Data a => a -> Int
Compute size of an arbitrary data structure
glength :: GenericQ Int
Count the number of immediate subterms of the given term
gdepth :: GenericQ Int
Determine depth of the given term
gcount :: GenericQ Bool -> GenericQ Int
Determine the number of all suitable nodes in a given term
gnodecount :: GenericQ Int
Determine the number of all nodes in a given term
gtypecount :: Typeable a => a -> GenericQ Int
Determine the number of nodes of a given type in a given term
gfindtype :: (Data x, Typeable y) => x -> Maybe y
Find (unambiguously) an immediate subterm of a given type
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