Data.Field

Data.Field provides immutable field type for record-style operations.

Field

data Field m record a

Normal field, which contain getter, setter and modifier.

Since fmr-0.2, you can also combine fmr fields using (.) and id from the Category class:

   outer :: (Monad m) => Field m outer inner
   inner :: (Monad m) => Field m inner value
   
   field :: (Monad m) => Field m outer value
   field =  outer.inner
 

Constructors

Field

Fields

• getField :: !(GetterFor m record a)

  Field getter

• setField :: !(SetterFor m record a)

  Field setter

• modifyField :: !(ModifierFor m record a)

  Field modifier

• modifyFieldM :: !(ModifierMFor m record a)

  Monadic field modifier

Instances

FieldSwitch Field

Defined in Data.Field

Methods

switchRecord :: (Monad m, IsSwitch a) => Field m record a -> record -> Int -> m ()

FieldModify Field

Defined in Data.Field

Methods

modifyRecord :: Monad m => Field m record a -> record -> (a -> a) -> m a

modifyRecordM :: (Monad m, FieldGet Field) => Field m record a -> record -> (a -> m a) -> m a

FieldSet Field

Defined in Data.Field

Methods

setRecord :: Monad m => Field m record a -> record -> a -> m ()

FieldGet Field

Defined in Data.Field

Methods

getRecord :: Monad m => Field m record a -> record -> m a

Monad m => Category (Field m :: Type -> Type -> Type)

Defined in Data.Field

Methods

id :: forall (a :: k). Field m a a

(.) :: forall (b :: k) (c :: k) (a :: k). Field m b c -> Field m a b -> Field m a c

sfield :: Monad m => GetterFor m record a -> SetterFor m record a -> Field m record a

sfield creates new field from given getter and setter.

type GetterFor m record a = record -> m a

Getter type.

type SetterFor m record a = record -> a -> m ()

Setter type.

type ModifierFor m record a = record -> (a -> a) -> m a

Modifier type.

type ModifierMFor m record a = record -> (a -> m a) -> m a

Monadic modifier type.

IsMVar and MonadVar

class (Monad m, MonadVar m) => IsMVar m var where

The IsMVar class provides this field for entire record access.

Please note that you cannot create IsMVar and MonadVar instances for some monad separately.

Methods

this :: Field m (var a) a

this is common variable access field.

var :: a -> m (var a)

Create and initialize new mutable variable.

Instances

IsMVar IO IORef

Defined in Data.Field

Methods

this :: Field IO (IORef a) a

var :: a -> IO (IORef a)

IsMVar IO MVar

Defined in Data.Field

Methods

this :: Field IO (MVar a) a

var :: a -> IO (MVar a)

IsMVar STM TVar

Defined in Data.Field

Methods

this :: Field STM (TVar a) a

var :: a -> STM (TVar a)

IsMVar (ST s) (STRef s)

Defined in Data.Field

Methods

this :: Field (ST s) (STRef s a) a

var :: a -> ST s (STRef s a)

class (Monad m, IsMVar m (Var m)) => MonadVar m

MonadVar is a class of monads for which defined at least one type of mutable variable.

Note that a variable of type (Var m) should be as simple possible for a given monad. I only has to implement the basic operations triad: read, write and update (which don't have to be atomic).

Associated Types

type Var m :: Type -> Type

(Var m) is type of mutable variable in monad m.

Instances

MonadVar IO

Defined in Data.Field

Associated Types

type Var IO :: Type -> Type

MonadVar STM

Defined in Data.Field

Associated Types

type Var STM :: Type -> Type

MonadVar (ST s)

Defined in Data.Field

Associated Types

type Var (ST s) :: Type -> Type