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 -> (t -> s -> s) -> GenericQ (s -> t) -> GenericQ t

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

Source

Apply a transformation everywhere in bottom-up manner

everywhere' :: (forall a . Data a => a -> a) -> forall a . Data a => a -> a

Source

Apply a transformation everywhere in top-down manner

everywhereBut :: GenericQ Bool -> GenericT -> GenericT

Source

Variation on everywhere with an extra stop condition

everywhereM :: Monad m => GenericM m -> GenericM m

Source

Monadic variation on everywhere

somewhere :: MonadPlus m => GenericM m -> GenericM m

Source

Apply a monadic transformation at least somewhere

everything :: (r -> r -> r) -> GenericQ r -> GenericQ r

Source

Summarise all nodes in top-down, left-to-right order

listify :: Typeable r => (r -> Bool) -> GenericQ [r]

Source

Get a list of all entities that meet a predicate

something :: GenericQ (Maybe u) -> GenericQ (Maybe u)

Source

Look up a subterm by means of a maybe-typed filter

synthesize :: s -> (t -> s -> s) -> GenericQ (s -> t) -> GenericQ t

Source

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

Source

Compute size of an arbitrary data structure

glength :: GenericQ Int

Source

Count the number of immediate subterms of the given term

gdepth :: GenericQ Int

Source

Determine depth of the given term

gcount :: GenericQ Bool -> GenericQ Int

Source

Determine the number of all suitable nodes in a given term