Name: data-accessor Version: 0.2.0.2 License: BSD3 License-File: LICENSE Author: Henning Thielemann , Luke Palmer Maintainer: Henning Thielemann Homepage: http://www.haskell.org/haskellwiki/Record_access Package-URL: http://code.haskell.org/data-accessor/ Category: Data -- Portability: Haskell98 Build-Type: Simple Build-Depends: base>=1.0, array >=0.1 && <1, containers >=0.1 && <1, transformers >=0.0.1 && <0.2 Synopsis: Utilities for accessing and manipulating fields of records Description: In Haskell 98 the name of a record field is automatically also the name of a function which gets the value of the according field. E.g. if we have . data Pair a b = Pair {first :: a, second :: b} . then . > first :: Pair a b -> a > second :: Pair a b -> b . However for setting or modifying a field value we need to use some syntactic sugar, which is often clumsy. . modifyFirst :: (a -> a) -> (Pair a b -> Pair a b) modifyFirst f r\@(Pair {first=a}) = r{first = f a} . With this package you can define record field accessors which allow setting, getting and modifying values easily. The package clearly demonstrates the power of the functional approach: You can combine accessors of a record and sub-records, to make the access look like the fields of the sub-record belong to the main record. . Example: . > *Data.Accessor.Example> (first^:second^=10) (('b',7),"hallo") > (('b',10),"hallo") . You can easily manipulate record fields in a 'Control.Monad.State.State' monad, you can easily code Show instances that use the Accessor syntax and you can parse binary streams into records. See @Data.Accessor.Example@ for demonstration of all features. . It would be great if in revised Haskell versions the names of record fields are automatically 'Data.Accessor.Accessor's rather than plain @get@ functions. The package @data-accessor-template@ provides Template Haskell functions for automated generation of 'Data.Acesssor.Accessor's. GHC-Options: -Wall Tested-With: GHC==6.4.1 && ==6.8.2 Hs-Source-Dirs: src Exposed-Modules: Data.Accessor Data.Accessor.Basic Data.Accessor.Container Data.Accessor.Show Data.Accessor.Tuple Data.Accessor.BinaryRead Data.Accessor.MonadState Other-Modules: Data.Accessor.Example