Generic data types in Haskell

Utilities for GHC.Generics.

Generic deriving for standard classes

Supported classes that GHC currently can’t derive: Semigroup, Monoid, Applicative, Alternative, Eq1, Ord1, Show1.

Other classes from base are also supported, even though GHC can already derive them:

• Eq, Ord, Enum, Bounded, Show (standard);
• Functor, Foldable, Traversable (via extensions, DeriveFunctor, etc.).

(Read is currently not implemented.)

To derive type classes defined elsewhere, it might be worth taking a look at one-liner.

Type metadata

Extract type names, constructor names, number and arities of constructors, etc..

Related links

generic-data aims to subsume generic deriving features of the following packages:

• semigroups: generic Semigroup, Monoid, but with a heavy dependency footprint.
• transformers-compat: generic Eq1, Ord1, Show1.
• generic-deriving: doesn’t derive the classes in base (defines clones of these classes as a toy example); has Template Haskell code to derive Generic.

Here are other relevant links.

• deriving-compat: deriving with Template Haskell.
• one-liner: another approach to using GHC.Generics to derive instances of many type classes, including but not restricted to the above classes (this is done in one-liner-instances).
• singletons, first-class-families (second one written by me) libraries for dependently-typed programming in Haskell.

All contributions are welcome. Open an issue or a pull request on Github!