Build lenses (and traversals) with a sensible default configuration.

 makeLenses = makeLensesWith lensRules

Derive lenses and traversals, specifying explicit pairings of (fieldName, lensName).

If you map multiple names to the same label, and it is present in the same constructor then this will generate a Traversal.

e.g.

 makeLensesFor [("_foo", "fooLens"), ("baz", "lbaz")] ''Foo
 makeLensesFor [("_barX", "bar"), ("_barY", "bar")] ''Bar

Make lenses and traversals for a type, and create a class when the type has no arguments.

e.g.

 data Foo = Foo { _fooX, _fooY :: Int }
 makeClassy ''Foo

will create

 class HasFoo t where
   foo :: Simple Lens t Foo
 instance HasFoo Foo where foo = id
 fooX, fooY :: HasFoo t => Simple Lens t Int

 makeClassy = makeLensesWith classyRules

Derive lenses and traversals, using a named wrapper class, and specifying explicit pairings of (fieldName, traversalName).

Example usage:

 makeClassyFor "HasFoo" "foo" [("_foo", "fooLens"), ("bar", "lbar")] ''Foo

Make a top level isomorphism injecting into the type.

The supplied name is required to be for a type with a single constructor that has a single argument.

e.g.

 newtype List a = List [a]
 makeIso ''List

will create

 list :: Iso [a] [b] (List a) (List b)

 makeIso = makeLensesWith isoRules

Generate a Prism for each constructor of a data type.

Build Wrapped instance for a given newtype

 makeFields = makeFieldsWith defaultFieldRules

Build lenses with a custom configuration.

Make fields with the specified FieldRules.

Default LensRules.

 defaultFieldRules = camelCaseFields

Field rules for fields in the form prefixFieldname

Field rules for fields in the form _prefix_fieldname

This configuration describes the options we'll be using to make isomorphisms or lenses.

Rules for making fairly simple partial lenses, ignoring the special cases for isomorphisms and traversals, and not making any classes.

Rules for making lenses and traversals that precompose another Lens.

Rules for making an isomorphism from a data type.

Lens' to access the convention for naming top level isomorphisms in our LensRules.

Defaults to lowercasing the first letter of the constructor.

Lens' to access the convention for naming fields in our LensRules.

Defaults to stripping the _ off of the field name, lowercasing the name, and rejecting the field if it doesn't start with an '_'.

Retrieve options such as the name of the class and method to put in it to build a class around monomorphic data types.

Retrieve options such as the name of the class and method to put in it to build a class around monomorphic data types.

Flags for Lens construction

Only Generate valid Simple lenses.

Enables the generation of partial lenses, generating runtime errors for every constructor that does not have a valid definition for the Lens. This occurs when the constructor lacks the field, or has multiple fields mapped to the same Lens.

In the situations that a Lens would be partial, when partialLenses is used, this flag instead causes traversals to be generated. Only one can be used, and if neither are, then compile-time errors are generated.

Handle singleton constructors specially.

Use Iso for singleton constructors.

Expect a single constructor, single field newtype or data type.

Create the class if the constructor is Simple and the lensClass rule matches.

Create the instance if the constructor is Simple and the lensClass rule matches.

Die if the lensClass fails to match.

When building a singleton Iso (or Lens) for a record constructor, build both the Iso (or Lens) for the record and the one for the field.

Indicate whether or not to supply the signatures for the generated lenses.

Disabling this can be useful if you want to provide a more restricted type signature or if you want to supply hand-written haddocks.