547 lines
11 KiB
Haskell
547 lines
11 KiB
Haskell
{-# LANGUAGE RankNTypes #-}
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module Lets.OpticPolyLens (
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Lens(..)
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, getsetLaw
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, setgetLaw
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, setsetLaw
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, get
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, set
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, modify
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, (%~)
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, fmodify
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, (|=)
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, fstL
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, sndL
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, mapL
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, setL
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, compose
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, (|.)
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, identity
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, product
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, (***)
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, choice
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, (|||)
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, cityL
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, countryL
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, streetL
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, suburbL
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, localityL
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, ageL
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, nameL
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, addressL
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, intAndIntL
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, intAndL
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, getSuburb
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, setStreet
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, getAgeAndCountry
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, setCityAndLocality
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, getSuburbOrCity
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, setStreetOrState
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, modifyCityUppercase
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, modifyIntandLengthEven
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) where
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import Data.Bool(bool)
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import Data.Char(toUpper)
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import Data.Map(Map)
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import qualified Data.Map as Map(insert, delete, lookup)
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import Data.Set(Set)
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import qualified Data.Set as Set(insert, delete, member)
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import Lets.Data
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import Prelude hiding (product)
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-- $setup
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-- >>> import qualified Data.Map as Map(fromList)
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-- >>> import qualified Data.Set as Set(fromList)
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-- >>> import Data.Char(ord)
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data Lens s t a b =
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Lens
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(forall f. Functor f => (a -> f b) -> s -> f t)
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get ::
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Lens s t a b
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-> s
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-> a
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get (Lens r) =
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getConst . r Const
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set ::
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Lens s t a b
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-> s
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-> b
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-> t
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set (Lens r) a b =
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getIdentity (r (const (Identity b)) a)
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-- | The get/set law of lenses. This function should always return @True@.
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getsetLaw ::
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Eq s =>
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Lens s s a a
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-> s
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-> Bool
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getsetLaw l =
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\a -> set l a (get l a) == a
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-- | The set/get law of lenses. This function should always return @True@.
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setgetLaw ::
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Eq a =>
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Lens s s a a
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-> s
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-> a
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-> Bool
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setgetLaw l a b =
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get l (set l a b) == b
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-- | The set/set law of lenses. This function should always return @True@.
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setsetLaw ::
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Eq s =>
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Lens s s a b
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-> s
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-> b
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-> b
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-> Bool
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setsetLaw l a b1 b2 =
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set l (set l a b1) b2 == set l a b2
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----
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-- |
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--
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-- >>> modify fstL (+1) (0 :: Int, "abc")
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-- (1,"abc")
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--
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-- >>> modify sndL (+1) ("abc", 0 :: Int)
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-- ("abc",1)
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--
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-- prop> let types = (x :: Int, y :: String) in modify fstL id (x, y) == (x, y)
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--
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-- prop> let types = (x :: Int, y :: String) in modify sndL id (x, y) == (x, y)
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modify ::
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Lens s t a b
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-> (a -> b)
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-> s
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-> t
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modify =
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error "todo: modify"
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-- | An alias for @modify@.
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(%~) ::
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Lens s t a b
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-> (a -> b)
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-> s
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-> t
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(%~) =
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modify
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infixr 4 %~
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-- |
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--
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-- >>> fstL .~ 1 $ (0 :: Int, "abc")
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-- (1,"abc")
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--
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-- >>> sndL .~ 1 $ ("abc", 0 :: Int)
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-- ("abc",1)
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--
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-- prop> let types = (x :: Int, y :: String) in set fstL (x, y) z == (fstL .~ z $ (x, y))
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--
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-- prop> let types = (x :: Int, y :: String) in set sndL (x, y) z == (sndL .~ z $ (x, y))
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(.~) ::
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Lens s t a b
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-> b
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-> s
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-> t
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(.~) =
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error "todo: (.~)"
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infixl 5 .~
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-- |
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--
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-- >>> fmodify fstL (+) (5 :: Int, "abc") 8
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-- (13,"abc")
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--
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-- >>> fmodify fstL (\n -> bool Nothing (Just (n * 2)) (even n)) (10, "abc")
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-- Just (20,"abc")
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--
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-- >>> fmodify fstL (\n -> bool Nothing (Just (n * 2)) (even n)) (11, "abc")
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-- Nothing
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fmodify ::
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Functor f =>
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Lens s t a b
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-> (a -> f b)
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-> s
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-> f t
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fmodify =
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error "todo: fmodify"
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-- |
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--
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-- >>> fstL |= Just 3 $ (7, "abc")
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-- Just (3,"abc")
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--
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-- >>> (fstL |= (+1) $ (3, "abc")) 17
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-- (18,"abc")
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(|=) ::
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Functor f =>
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Lens s t a b
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-> f b
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-> s
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-> f t
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(|=) =
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error "todo: (|=)"
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infixl 5 |=
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-- |
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--
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-- >>> modify fstL (*10) (3, "abc")
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-- (30,"abc")
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--
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-- prop> let types = (x :: Int, y :: String) in getsetLaw fstL (x, y)
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--
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-- prop> let types = (x :: Int, y :: String) in setgetLaw fstL (x, y) z
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--
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-- prop> let types = (x :: Int, y :: String) in setsetLaw fstL (x, y) z
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fstL ::
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Lens (a, x) (b, x) a b
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fstL =
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error "todo: fstL"
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-- |
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--
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-- >>> modify sndL (++ "def") (13, "abc")
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-- (13,"abcdef")
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--
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-- prop> let types = (x :: Int, y :: String) in getsetLaw sndL (x, y)
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--
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-- prop> let types = (x :: Int, y :: String) in setgetLaw sndL (x, y) z
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--
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-- prop> let types = (x :: Int, y :: String) in setsetLaw sndL (x, y) z
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sndL ::
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Lens (x, a) (x, b) a b
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sndL =
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error "todo: sndL"
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-- |
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--
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-- >>> get (mapL 3) (Map.fromList (map (\c -> (ord c - 96, c)) ['a'..'d']))
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-- Just 'c'
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--
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-- >>> get (mapL 33) (Map.fromList (map (\c -> (ord c - 96, c)) ['a'..'d']))
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-- Nothing
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--
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-- >>> set (mapL 3) (Map.fromList (map (\c -> (ord c - 96, c)) ['a'..'d'])) (Just 'X')
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-- fromList [(1,'a'),(2,'b'),(3,'X'),(4,'d')]
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--
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-- >>> set (mapL 33) (Map.fromList (map (\c -> (ord c - 96, c)) ['a'..'d'])) (Just 'X')
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-- fromList [(1,'a'),(2,'b'),(3,'c'),(4,'d'),(33,'X')]
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--
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-- >>> set (mapL 3) (Map.fromList (map (\c -> (ord c - 96, c)) ['a'..'d'])) Nothing
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-- fromList [(1,'a'),(2,'b'),(4,'d')]
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--
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-- >>> set (mapL 33) (Map.fromList (map (\c -> (ord c - 96, c)) ['a'..'d'])) Nothing
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-- fromList [(1,'a'),(2,'b'),(3,'c'),(4,'d')]
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mapL ::
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Ord k =>
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k
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-> Lens (Map k v) (Map k v) (Maybe v) (Maybe v)
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mapL =
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error "todo: mapL"
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-- |
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--
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-- >>> get (setL 3) (Set.fromList [1..5])
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-- True
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--
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-- >>> get (setL 33) (Set.fromList [1..5])
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-- False
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--
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-- >>> set (setL 3) (Set.fromList [1..5]) True
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-- fromList [1,2,3,4,5]
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--
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-- >>> set (setL 3) (Set.fromList [1..5]) False
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-- fromList [1,2,4,5]
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--
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-- >>> set (setL 33) (Set.fromList [1..5]) True
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-- fromList [1,2,3,4,5,33]
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--
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-- >>> set (setL 33) (Set.fromList [1..5]) False
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-- fromList [1,2,3,4,5]
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setL ::
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Ord k =>
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k
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-> Lens (Set k) (Set k) Bool Bool
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setL =
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error "todo: setL"
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-- |
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--
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-- >>> get (compose fstL sndL) ("abc", (7, "def"))
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-- 7
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--
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-- >>> set (compose fstL sndL) ("abc", (7, "def")) 8
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-- ("abc",(8,"def"))
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compose ::
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Lens s t a b
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-> Lens q r s t
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-> Lens q r a b
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compose =
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error "todo: compose"
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-- | An alias for @compose@.
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(|.) ::
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Lens s t a b
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-> Lens q r s t
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-> Lens q r a b
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(|.) =
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compose
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infixr 9 |.
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-- |
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--
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-- >>> get identity 3
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-- 3
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--
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-- >>> set identity 3 4
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-- 4
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identity ::
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Lens a b a b
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identity =
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error "todo: identity"
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-- |
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--
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-- >>> get (product fstL sndL) (("abc", 3), (4, "def"))
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-- ("abc","def")
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--
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-- >>> set (product fstL sndL) (("abc", 3), (4, "def")) ("ghi", "jkl")
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-- (("ghi",3),(4,"jkl"))
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product ::
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Lens s t a b
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-> Lens q r c d
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-> Lens (s, q) (t, r) (a, c) (b, d)
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product =
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error "todo: product"
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-- | An alias for @product@.
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(***) ::
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Lens s t a b
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-> Lens q r c d
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-> Lens (s, q) (t, r) (a, c) (b, d)
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(***) =
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product
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infixr 3 ***
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-- |
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--
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-- >>> get (choice fstL sndL) (Left ("abc", 7))
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-- "abc"
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--
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-- >>> get (choice fstL sndL) (Right ("abc", 7))
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-- 7
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--
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-- >>> set (choice fstL sndL) (Left ("abc", 7)) "def"
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-- Left ("def",7)
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--
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-- >>> set (choice fstL sndL) (Right ("abc", 7)) 8
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-- Right ("abc",8)
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choice ::
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Lens s t a b
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-> Lens q r a b
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-> Lens (Either s q) (Either t r) a b
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choice =
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error "todo: choice"
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-- | An alias for @choice@.
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(|||) ::
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Lens s t a b
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-> Lens q r a b
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-> Lens (Either s q) (Either t r) a b
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(|||) =
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choice
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infixr 2 |||
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----
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type Lens' a b =
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Lens a a b b
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cityL ::
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Lens' Locality String
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cityL =
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Lens
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(\p (Locality c t y) -> fmap (\c' -> Locality c' t y) (p c))
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stateL ::
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Lens' Locality String
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stateL =
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Lens
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(\p (Locality c t y) -> fmap (\t' -> Locality c t' y) (p t))
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countryL ::
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Lens' Locality String
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countryL =
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Lens
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(\p (Locality c t y) -> fmap (\y' -> Locality c t y') (p y))
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streetL ::
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Lens' Address String
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streetL =
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Lens
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(\p (Address t s l) -> fmap (\t' -> Address t' s l) (p t))
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suburbL ::
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Lens' Address String
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suburbL =
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Lens
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(\p (Address t s l) -> fmap (\s' -> Address t s' l) (p s))
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localityL ::
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Lens' Address Locality
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localityL =
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Lens
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(\p (Address t s l) -> fmap (\l' -> Address t s l') (p l))
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ageL ::
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Lens' Person Int
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ageL =
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Lens
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(\p (Person a n d) -> fmap (\a' -> Person a' n d) (p a))
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nameL ::
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Lens' Person String
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nameL =
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Lens
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(\p (Person a n d) -> fmap (\n' -> Person a n' d) (p n))
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addressL ::
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Lens' Person Address
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addressL =
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Lens
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(\p (Person a n d) -> fmap (\d' -> Person a n d') (p d))
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intAndIntL ::
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Lens' (IntAnd a) Int
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intAndIntL =
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Lens
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(\p (IntAnd n a) -> fmap (\n' -> IntAnd n' a) (p n))
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-- lens for polymorphic update
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intAndL ::
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Lens (IntAnd a) (IntAnd b) a b
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intAndL =
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Lens
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(\p (IntAnd n a) -> fmap (\a' -> IntAnd n a') (p a))
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-- |
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--
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-- >>> get (suburbL |. addressL) fred
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-- "Fredville"
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--
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-- >>> get (suburbL |. addressL) mary
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-- "Maryland"
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getSuburb ::
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Person
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-> String
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getSuburb =
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error "todo: getSuburb"
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-- |
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--
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-- >>> setStreet fred "Some Other St"
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-- Person 24 "Fred" (Address "Some Other St" "Fredville" (Locality "Fredmania" "New South Fred" "Fredalia"))
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--
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-- >>> setStreet mary "Some Other St"
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-- Person 28 "Mary" (Address "Some Other St" "Maryland" (Locality "Mary Mary" "Western Mary" "Maristan"))
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setStreet ::
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Person
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-> String
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-> Person
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setStreet =
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error "todo: setStreet"
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-- |
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--
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-- >>> getAgeAndCountry (fred, maryLocality)
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-- (24,"Maristan")
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--
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-- >>> getAgeAndCountry (mary, fredLocality)
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-- (28,"Fredalia")
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getAgeAndCountry ::
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(Person, Locality)
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-> (Int, String)
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getAgeAndCountry =
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error "todo: getAgeAndCountry"
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-- |
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--
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-- >>> setCityAndLocality (fred, maryAddress) ("Some Other City", fredLocality)
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-- (Person 24 "Fred" (Address "15 Fred St" "Fredville" (Locality "Some Other City" "New South Fred" "Fredalia")),Address "83 Mary Ln" "Maryland" (Locality "Fredmania" "New South Fred" "Fredalia"))
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--
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-- >>> setCityAndLocality (mary, fredAddress) ("Some Other City", maryLocality)
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-- (Person 28 "Mary" (Address "83 Mary Ln" "Maryland" (Locality "Some Other City" "Western Mary" "Maristan")),Address "15 Fred St" "Fredville" (Locality "Mary Mary" "Western Mary" "Maristan"))
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setCityAndLocality ::
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(Person, Address) -> (String, Locality) -> (Person, Address)
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setCityAndLocality =
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error "todo: setCityAndLocality"
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-- |
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--
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-- >>> getSuburbOrCity (Left maryAddress)
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-- "Maryland"
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--
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-- >>> getSuburbOrCity (Right fredLocality)
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-- "Fredmania"
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getSuburbOrCity ::
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Either Address Locality
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-> String
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getSuburbOrCity =
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get (suburbL ||| cityL)
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-- |
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--
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-- >>> setStreetOrState (Right maryLocality) "Some Other State"
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-- Right (Locality "Mary Mary" "Some Other State" "Maristan")
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--
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-- >>> setStreetOrState (Left fred) "Some Other St"
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-- Left (Person 24 "Fred" (Address "Some Other St" "Fredville" (Locality "Fredmania" "New South Fred" "Fredalia")))
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setStreetOrState ::
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Either Person Locality
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-> String
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-> Either Person Locality
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setStreetOrState =
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set (streetL |. addressL ||| stateL)
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-- |
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--
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-- >>> modifyCityUppercase fred
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-- Person 24 "Fred" (Address "15 Fred St" "Fredville" (Locality "FREDMANIA" "New South Fred" "Fredalia"))
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--
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-- >>> modifyCityUppercase mary
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-- Person 28 "Mary" (Address "83 Mary Ln" "Maryland" (Locality "MARY MARY" "Western Mary" "Maristan"))
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modifyCityUppercase ::
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Person
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-> Person
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modifyCityUppercase =
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cityL |. localityL |. addressL %~ map toUpper
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-- |
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--
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-- >>> modify intAndL (even . length) (IntAnd 10 "abc")
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-- IntAnd 10 False
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--
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-- >>> modify intAndL (even . length) (IntAnd 10 "abcd")
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-- IntAnd 10 True
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modifyIntandLengthEven ::
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IntAnd [a]
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-> IntAnd Bool
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modifyIntandLengthEven =
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intAndL %~ even . length
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