Generics.EMGM.Common.Base2

emgm-0.3: Extensible and Modular Generics for the Masses

Portability	non-portable
Stability	experimental
Maintainer	generics@haskell.org

Contents

Generic function class
Representation dispatcher classes

Description

Summary: Type classes used for generic functions with two generic arguments.

Generic functions using two generic arguments are defined as instances of Generic2. This class contains all of the methods (called "type cases" in datatype-generic language) used to define the run-time type representation of a datatype.

Generic2-based functions have a representation dispatcher type class FRep2.

The functions included with the library are:

Generics.EMGM.Functions.Map

Synopsis

class Generic2 g where

rconstant2 :: (Enum a, Eq a, Ord a, Read a, Show a) => g a a

rint2 :: g Int Int

rinteger2 :: g Integer Integer

rfloat2 :: g Float Float

rdouble2 :: g Double Double

rchar2 :: g Char Char

runit2 :: g Unit Unit

rsum2 :: g a1 a2 -> g b1 b2 -> g (a1 :+: b1) (a2 :+: b2)

rprod2 :: g a1 a2 -> g b1 b2 -> g (a1 :*: b1) (a2 :*: b2)

rcon2 :: ConDescr -> g a1 a2 -> g a1 a2

rtype2 :: EP a2 a1 -> EP b2 b1 -> g a1 b1 -> g a2 b2

class FRep2 g f where

frep2 :: g a b -> g (f a) (f b)

class BiFRep2 g f where

bifrep2 :: g a1 b1 -> g a2 b2 -> g (f a1 a2) (f b1 b2)

Generic function class

class Generic2 g where

Source

This class forms the foundation for defining generic functions with two generic arguments. Each method represents a type case. The class includes cases for primitive types, cases for the structural representation, and the rtype case for adding support for new datatypes.

Methods

rconstant2 :: (Enum a, Eq a, Ord a, Read a, Show a) => g a a

Source

Many functions perform the same operation on the non-structural cases (as well as Unit). The cases for constant datatypes (Int, Integer, Float, Double, Char, and Unit) have a default implementation of rconstant2, thus a generic function may only override rconstant2 if desired. Note that there is no default implementation for rconstant2 itself.

The class context represents the intersection set of supported type classes.

rint2 :: g Int Int

Source

Case for the primitive type Int. (Default implementation: rconstant2.)

rinteger2 :: g Integer Integer

Source

Case for the primitive type Integer. (Default implementation: rconstant2.)

rfloat2 :: g Float Float

Source

Case for the primitive type Float. (Default implementation: rconstant2.)

rdouble2 :: g Double Double

Source

Case for the primitive type Double. (Default implementation: rconstant2.)

rchar2 :: g Char Char

Source

Case for the primitive type Char. (Default implementation: rconstant2.)

runit2 :: g Unit Unit

Source

Case for the structural representation type Unit. It is used to represent a constructor with no arguments. (Default implementation: rconstant2.)

rsum2 :: g a1 a2 -> g b1 b2 -> g (a1 :+: b1) (a2 :+: b2)

Source

Case for the structural representation type :+: (sum). It is used to represent alternative choices between constructors. (No default implementation.)

rprod2 :: g a1 a2 -> g b1 b2 -> g (a1 :*: b1) (a2 :*: b2)

Source

Case for the structural representation type :*: (product). It is used to represent multiple arguments to a constructor. (No default implementation.)

rcon2 :: ConDescr -> g a1 a2 -> g a1 a2

Source

Case for constructors. It is used to hold the meta-information about a constructor (ConDescr), e.g. name, arity, fixity, etc. (Since most generic functions do not use rcon and simply pass the value through, the default implementation is const id.)

rtype2 :: EP a2 a1 -> EP b2 b1 -> g a1 b1 -> g a2 b2

Source

Case for datatypes. This method is used to define the structural representation of an arbitrary Haskell datatype. The first two arguments are the embedding-projection pairs, necessary for establishing the isomorphisms between datatype and representation of the two generic types. The third argument is the run-time representation using the methods of Generic2. (No default implementation.)