Control.Lens.TH

Documentation

data LensRules

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

Constructors

LensRules (String -> Maybe String) (String -> Maybe String) (String -> Maybe (String, String)) (Set LensFlag)

lensIso :: Simple Lens LensRules (String -> Maybe String)

Lens to access the convention for naming top level isomorphisms in our lens rules

Defaults to lowercasing the first letter of the constructor.

lensField :: Simple Lens LensRules (String -> Maybe String)

Lens to access the convention for naming fields in our lens rules

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

lensClass :: Simple Lens LensRules (String -> Maybe (String, String))

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

lensFlags :: Simple Lens LensRules (Set LensFlag)

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

data LensFlag

Flags for lens construction

Constructors

SimpleLenses

SingletonAndField

SingletonIso

HandleSingletons

SingletonRequired

CreateClass

CreateInstance

ClassRequired

Instances

Eq LensFlag

Ord LensFlag

Read LensFlag

Show LensFlag

simpleLenses :: Simple Lens LensRules Bool

Only Generate valid Simple Lens lenses

handleSingletons :: Simple Lens LensRules Bool

Handle singleton constructors specially

singletonIso :: Simple Lens LensRules Bool

Use Iso for singleton constructors

singletonRequired :: Simple Lens LensRules Bool

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

createClass :: Simple Lens LensRules Bool

Create the class if the constructor is simple and the lensClass rule matches

createInstance :: Simple Lens LensRules Bool

Create the instance if the constructor is simple and the lensClass rule matches

classRequired :: Simple Lens LensRules Bool

Die if the lensClass fails to match

Constructing Lenses Automatically

makeClassy :: Name -> Q [Dec]

Make 'classy lenses' for a type

 makeClassy = makeLensesWith classyRules

makeClassyFor :: String -> String -> [(String, String)] -> Name -> Q [Dec]

Derive lenses, specifying explicit pairings of (fieldName, lensName) using a wrapper class.

Example usage:

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

makeIso :: Name -> Q [Dec]

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

 makeIso = makeLensesWith isoRules

makeLenses :: Name -> Q [Dec]

Build lenses with a sensible default configuration

 makeLenses = makeLensesWith lensRules

makeLensesFor :: [(String, String)] -> Name -> Q [Dec]

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

Example usage:

 makeLensesFor [("_foo", "fooLens"), ("bar", "lbar")] ''Foo

makeLensesWith :: LensRules -> Name -> Q [Dec]

Build lenses with a custom configuration

lensRules :: LensRules

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

classyRules :: LensRules

Rules for making lenses that precompose another lens.

isoRules :: LensRules

Rules for making an isomorphism from a data type

defaultRules :: LensRules

Default lens rules