Strongweak.Weaken

Weaken class

class Weaken a where

Transform an a to a Weaken a.

A given strong type a has exactly one associated weak type Weaken a. Multiple strong types may weaken to the same weak type.

Law: a === b -> weaken a === weaken b

Instances should either handle an invariant, or decompose. See Strongweak for a discussion on this design.

Associated Types

type Weak a :: Type

The type to weaken to.

Methods

weaken :: a -> Weak a

Transform a strong value to its associated weak one.

Instances

Weaken Int16

Defined in Strongweak.Weaken

Associated Types

type Weak Int16

Methods

weaken :: Int16 -> Weak Int16

Weaken Int32

Defined in Strongweak.Weaken

Associated Types

type Weak Int32

Methods

weaken :: Int32 -> Weak Int32

Weaken Int64

Defined in Strongweak.Weaken

Associated Types

type Weak Int64

Methods

weaken :: Int64 -> Weak Int64

Weaken Int8

Defined in Strongweak.Weaken

Associated Types

type Weak Int8

Methods

weaken :: Int8 -> Weak Int8

Weaken Word16

Defined in Strongweak.Weaken

Associated Types

type Weak Word16

Methods

weaken :: Word16 -> Weak Word16

Weaken Word32

Defined in Strongweak.Weaken

Associated Types

type Weak Word32

Methods

weaken :: Word32 -> Weak Word32

Weaken Word64

Defined in Strongweak.Weaken

Associated Types

type Weak Word64

Methods

weaken :: Word64 -> Weak Word64

Weaken Word8

Defined in Strongweak.Weaken

Associated Types

type Weak Word8

Methods

weaken :: Word8 -> Weak Word8

Weaken a => Weaken (Identity a)

Decomposer.

Defined in Strongweak.Weaken

Associated Types

type Weak (Identity a)

Methods

weaken :: Identity a -> Weak (Identity a)

Weaken (NonEmpty a)

Weaken non-empty lists into plain lists.

Defined in Strongweak.Weaken

Associated Types

type Weak (NonEmpty a)

Methods

weaken :: NonEmpty a -> Weak (NonEmpty a)

Weaken a => Weaken (Maybe a)

Decomposer.

Defined in Strongweak.Weaken

Associated Types

type Weak (Maybe a)

Methods

weaken :: Maybe a -> Weak (Maybe a)

Weaken a => Weaken [a]

Decomposer. Weaken every element in a list.

Defined in Strongweak.Weaken

Associated Types

type Weak [a]

Methods

weaken :: [a] -> Weak [a]

(Weaken a, Weaken b) => Weaken (Either a b)

Decomposer.

Defined in Strongweak.Weaken

Associated Types

type Weak (Either a b)

Methods

weaken :: Either a b -> Weak (Either a b)

Weaken (Vector n a)

Weaken sized vectors into plain lists.

Defined in Strongweak.Weaken

Associated Types

type Weak (Vector n a)

Methods

weaken :: Vector n a -> Weak (Vector n a)

(Weaken a, Weaken b) => Weaken (a, b)

Decomposer.

Defined in Strongweak.Weaken

Associated Types

type Weak (a, b)

Methods

weaken :: (a, b) -> Weak (a, b)

Weaken a => Weaken (Const a b)

Decomposer.

Defined in Strongweak.Weaken

Associated Types

type Weak (Const a b)

Methods

weaken :: Const a b -> Weak (Const a b)

Weaken (Refined p a)

Strip the refinement from refined types.

Defined in Strongweak.Weaken

Associated Types

type Weak (Refined p a)

Methods

weaken :: Refined p a -> Weak (Refined p a)

liftWeakF :: Weaken a => (Weak a -> b) -> a -> b

Lift a function on a weak type to the associated strong type.

SW helper

data Strength

Strength enumeration: is it strong, or weak?

Primarily interesting at the type level (using DataKinds).

Constructors

Strong

Weak

type family SW (s :: Strength) a :: Type where ...

Get either the strong or weak representation of a type, depending on the type-level "switch" provided.

This is intended to be used in data types that take a Strength type. Define your type using strong fields wrapped in SW s. You then get the weak representation for free, using the same definition.

data A (s :: Strength) = A
  { a1 :: SW s Word8
  , a2 :: String }

Equations

SW 'Strong a = a

SW 'Weak a = Weak a