Copyright	(c) 2016, Peter Trško
License	BSD3
Maintainer	peter.trsko@gmail.com
Stability	experimental
Portability	CPP, NoImplicitPrelude
Safe Haskell	None
Language	Haskell2010

Data.OverloadedRecords.TH

Contents

Derive OverloadedRecordFields instances
- Customize Derivation Process
Low-level Deriving Mechanism

Description

Derive magic instances for OverloadedRecordFields.

Synopsis

Derive OverloadedRecordFields instances

overloadedRecord Source

Arguments

:: DeriveOverloadedRecordsParams	Parameters for customization of deriving process. Use `def` to get default behaviour.
-> Name	Name of the type for which magic instances should be derived.
-> DecsQ

Derive magic OverloadedRecordFields instances for specified type.

overloadedRecords Source

Arguments

:: DeriveOverloadedRecordsParams	Parameters for customization of deriving process. Use `def` to get default behaviour.
-> [Name]	Names of the types for which magic instances should be derived.
-> DecsQ

Derive magic OverloadedRecordFields instances for specified types.

overloadedRecordFor Source

Arguments

:: Name	Name of the type for which magic instances should be derived.
-> (DeriveOverloadedRecordsParams -> DeriveOverloadedRecordsParams)	Function that modifies parameters for customization of deriving process.
-> DecsQ

Derive magic OverloadedRecordFields instances for specified type.

Similar to overloadedRecords, but instead of DeriveOverloadedRecordsParams value it takes function which can modify its default value.

data Coordinates2D a
    { coordinateX :: a
    , coordinateY :: a
    }

overloadedRecordsFor ''Coordinates2D
    $ #fieldDerivation .~ \_ _ _ -> \case
        Nothing -> Nothing
        Just field -> lookup field
           [ ("coordinateX", GetterOnlyField "x" Nothing)
           , ("coordinateY", GetterOnlyField "y" Nothing)
           ]

overloadedRecordsFor Source

Arguments

:: [Name]	Names of the types for which magic instances should be derived.
-> (DeriveOverloadedRecordsParams -> DeriveOverloadedRecordsParams)	Function that modifies parameters for customization of deriving process.
-> DecsQ

Derive magic OverloadedRecordFields instances for specified types.

Customize Derivation Process

data DeriveOverloadedRecordsParams Source

Parameters for customization of deriving process. Use def to get default behaviour.

Instances

Generic DeriveOverloadedRecordsParams Source
Default DeriveOverloadedRecordsParams Source	`def` = `DeriveOverloadedRecordsParams` { strictFields = `False` , `fieldDerivation` = `defaultFieldDerivation` }
HasField "fieldDerivation" DeriveOverloadedRecordsParams FieldDerivation Source
ModifyField "fieldDerivation" DeriveOverloadedRecordsParams DeriveOverloadedRecordsParams FieldDerivation FieldDerivation Source
type Rep DeriveOverloadedRecordsParams Source
type FieldType "fieldDerivation" DeriveOverloadedRecordsParams = FieldDerivation Source
type UpdateType "fieldDerivation" DeriveOverloadedRecordsParams FieldDerivation = DeriveOverloadedRecordsParams Source

fieldDerivation :: IsLabel "fieldDerivation" a => a Source

Overloaded label that can be used for accessing function of type FieldDerivation from DeriveOverloadedRecordsParams.

This definition is available only if compiled with GHC <8.

type FieldDerivation Source

Arguments

= String	Name of the type, of which this field is part of.
-> String	Name of the constructor, of which this field is part of.
-> Word	Field position as an argument of the constructor it is part of. Indexing starts from zero.
-> Maybe String	Name of the field (record) accessor; `Nothing` means that there is no record accessor defined for it.
-> Maybe OverloadedField	Describes how overloaded record field should be generated for this specific constructor field. `Nothing` means that no overloaded record field should be derived. See also `OverloadedField` for details.

Type signature of a function that can customize the derivation of each individual overloaded record field.

If field has an selector then the function will get its name or Nothing otherwise. Function has to return Nothing in case when generating overloaded record field instances is not desired.

data OverloadedField Source

Describes what should be the name of overloaded record field, and can also provide custom implementation of getter and setter.

Constructors

GetterOnlyField String (Maybe ExpQ)	Derive only getter instances. If second argument is `Just`, then it contains custom definition of getter function.
GetterAndSetterField String (Maybe (ExpQ, ExpQ))	Derive only getter instances. If second argument is `Just`, then it contains custom definitions of getter and setter functions, respectively.

Instances

Generic OverloadedField Source
HasField "fieldDerivation" DeriveOverloadedRecordsParams FieldDerivation Source
ModifyField "fieldDerivation" DeriveOverloadedRecordsParams DeriveOverloadedRecordsParams FieldDerivation FieldDerivation Source
type Rep OverloadedField Source
type UpdateType "fieldDerivation" DeriveOverloadedRecordsParams FieldDerivation = DeriveOverloadedRecordsParams Source

defaultFieldDerivation :: FieldDerivation Source

Function used by default value of DeriveOverloadedRecordsParams.

defaultMakeFieldName Source

Arguments

:: String	Name of the type, of which this field is part of.
-> String	Name of the constructor, of which this field is part of.
-> Word	Field position as an argument of the constructor it is part of. Indexing starts from zero.
-> Maybe String	Name of the field (record) accessor; `Nothing` means that there is no record accessor defined for it.
-> Maybe String	Overloaded record field name to be used for this specific constructor field; `Nothing` means that there shouldn't be a label associated with it.

Suppose we have a weird type definition as this:

data SomeType a b c = SomeConstructor
    { _fieldX :: a
    , someTypeFieldY :: b
    , someConstructorFieldZ :: c
    , anythingElse :: (a, b, c)
    }

Then for each of those fields, defaultMakeFieldName will produce expected OverloadedLabel name:

```
_fieldX --> fieldX
```
```
someTypeFieldY --> fieldY
```
```
someConstructorFieldZ --> fieldZ
```
anythingElse is ignored

Low-level Deriving Mechanism

field Source

Arguments

:: String	Overloaded label name.
-> TypeQ	Record type.
-> TypeQ	Field type.
-> TypeQ	Record type after update.
-> TypeQ	Setter will set field to a value of this type.
-> ExpQ	Getter function.
-> ExpQ	Setter function.
-> DecsQ

Derive instances for overloaded record field, both getter and setter.

simpleField Source

Arguments

:: String	Overloaded label name.
-> TypeQ	Record type.
-> TypeQ	Field type.
-> ExpQ	Getter function.
-> ExpQ	Setter function.
-> DecsQ

Derive instances for overloaded record field, both getter and setter. Same as field, but record type is the same before and after update and so is the field type.

fieldGetter Source

Arguments

:: String	Overloaded label name.
-> TypeQ	Record type.
-> TypeQ	Field type
-> ExpQ	Getter function.
-> DecsQ

Derive instances for overloaded record field getter.

fieldSetter Source

Arguments

:: String	Overloaded label name.
-> TypeQ	Record type.
-> TypeQ	Field type.
-> TypeQ	Record type after update.
-> TypeQ	Setter will set field to a value of this type.
-> ExpQ	Setter function.
-> DecsQ

Derive instances for overloaded record field setter.

simpleFieldSetter Source

Arguments

:: String	Overloaded label name.
-> TypeQ	Record type.
-> TypeQ	Field type.
-> ExpQ	Setter function.
-> DecsQ

Derive instances for overloaded record field setter. Same as fieldSetter, but record type is the same before and after update and so is the field type.