move modules around
This commit is contained in:
Tony Morris
parent
e3f9926b05
commit
f960fb1bc7
|
|
@ -16,7 +16,7 @@ The exercises take into account various possible goals. For example, if you wish
|
|||
to study the history of lenses, then build up to the most recent theories, it is
|
||||
best to start at the `Lets.GetSetLens` module. If you wish to derive the
|
||||
structure of lenses from first principles, then derive the more modern theories,
|
||||
start at the `Lets.Lens.Lens` module.
|
||||
start at the `Lets.Lens` module.
|
||||
|
||||
Exercises can be recognised by filling in a function body that has a placeholder
|
||||
of `error "todo: <function-name>"`.
|
||||
|
|
@ -49,7 +49,7 @@ This series of exercises introduces a new representation of lenses, first
|
|||
described by Twan van Laarhoven. This representation also introduces a
|
||||
generalisation of lenses to permit *polymorphic update* of structures.
|
||||
|
||||
##### `Lets.Lens.Lens`
|
||||
##### `Lets.Lens`
|
||||
|
||||
This series of exercises starts at first principles to derive the concept of a
|
||||
lens, as it was first described by Twan van Laarhoven. The derivation then goes
|
||||
|
|
|
|||
|
|
@ -39,13 +39,12 @@ library
|
|||
hs-source-dirs: src
|
||||
|
||||
exposed-modules: Lets
|
||||
Lets.Choice
|
||||
Lets.Data
|
||||
Lets.GetSetLens
|
||||
Lets.Lens
|
||||
Lets.Lens.Choice
|
||||
Lets.Lens.Lens
|
||||
Lets.Lens.Profunctor
|
||||
Lets.OpticPolyLens
|
||||
Lets.Profunctor
|
||||
Lets.StoreLens
|
||||
|
||||
test-suite doctests
|
||||
|
|
|
|||
|
|
@ -1,9 +1,9 @@
|
|||
module Lets.Lens.Choice (
|
||||
module Lets.Choice (
|
||||
Choice(..)
|
||||
) where
|
||||
|
||||
import Lets.Data
|
||||
import Lets.Lens.Profunctor
|
||||
import Lets.Profunctor
|
||||
|
||||
diswap ::
|
||||
Profunctor p =>
|
||||
789
src/Lets/Lens.hs
789
src/Lets/Lens.hs
|
|
@ -1,7 +1,788 @@
|
|||
{-# LANGUAGE RankNTypes #-}
|
||||
|
||||
module Lets.Lens (
|
||||
module L
|
||||
fmapT
|
||||
, over
|
||||
, fmapTAgain
|
||||
, Set
|
||||
, sets
|
||||
, mapped
|
||||
, set
|
||||
, foldMapT
|
||||
, foldMapOf
|
||||
, foldMapTAgain
|
||||
, Fold
|
||||
, folds
|
||||
, folded
|
||||
, Get
|
||||
, get
|
||||
, Traversal
|
||||
, both
|
||||
, traverseLeft
|
||||
, traverseRight
|
||||
, Traversal'
|
||||
, Lens
|
||||
, Prism
|
||||
, _Left
|
||||
, _Right
|
||||
, prism
|
||||
, _Just
|
||||
, _Nothing
|
||||
, setP
|
||||
, getP
|
||||
, Prism'
|
||||
, modify
|
||||
, (%~)
|
||||
, (.~)
|
||||
, fmodify
|
||||
, (|=)
|
||||
, fstL
|
||||
, sndL
|
||||
, mapL
|
||||
, setL
|
||||
, compose
|
||||
, (|.)
|
||||
, identity
|
||||
, product
|
||||
, (***)
|
||||
, choice
|
||||
, (|||)
|
||||
, Lens'
|
||||
, cityL
|
||||
, stateL
|
||||
, countryL
|
||||
, streetL
|
||||
, suburbL
|
||||
, localityL
|
||||
, ageL
|
||||
, nameL
|
||||
, addressL
|
||||
, intAndIntL
|
||||
, intAndL
|
||||
, getSuburb
|
||||
, setStreet
|
||||
, getAgeAndCountry
|
||||
, setCityAndLocality
|
||||
, getSuburbOrCity
|
||||
, setStreetOrState
|
||||
, modifyCityUppercase
|
||||
, modifyIntAndLengthEven
|
||||
, traverseLocality
|
||||
, intOrIntP
|
||||
, intOrP
|
||||
, intOrLengthEven
|
||||
) where
|
||||
|
||||
import Lets.Lens.Choice as L
|
||||
import Lets.Lens.Lens as L
|
||||
import Lets.Lens.Profunctor as L
|
||||
import Control.Applicative(Applicative((<*>), pure))
|
||||
import Data.Bool(bool)
|
||||
import Data.Char(toUpper)
|
||||
import Data.Foldable(Foldable(foldMap))
|
||||
import Data.Functor((<$>))
|
||||
import Data.Map(Map)
|
||||
import qualified Data.Map as Map(insert, delete, lookup)
|
||||
import Data.Monoid(Monoid)
|
||||
import qualified Data.Set as Set(Set, insert, delete, member)
|
||||
import Data.Traversable(Traversable(traverse))
|
||||
import Lets.Data(AlongsideLeft(AlongsideLeft, getAlongsideLeft), AlongsideRight(AlongsideRight, getAlongsideRight), Identity(Identity, getIdentity), Const(Const, getConst), Tagged(Tagged, getTagged), IntOr(IntOrIs, IntOrIsNot), IntAnd(IntAnd), Person(Person), Locality(Locality), Address(Address))
|
||||
import Lets.Choice(Choice(left, right))
|
||||
import Lets.Profunctor(Profunctor(dimap))
|
||||
import Prelude hiding (product)
|
||||
|
||||
-- $setup
|
||||
-- >>> import qualified Data.Map as Map(fromList)
|
||||
-- >>> import qualified Data.Set as Set(fromList)
|
||||
-- >>> import Data.Char(ord)
|
||||
|
||||
-- Let's remind ourselves of Traversable, noting Foldable and Functor.
|
||||
--
|
||||
-- class (Foldable t, Functor t) => Traversable t where
|
||||
-- traverse ::
|
||||
-- Applicative f =>
|
||||
-- (a -> f b)
|
||||
-- -> t a
|
||||
-- -> f (t b)
|
||||
|
||||
-- | Observe that @fmap@ can be recovered from @traverse@ using @Identity@.
|
||||
--
|
||||
-- /Reminder:/ fmap :: Functor t => (a -> b) -> t a -> t b
|
||||
fmapT ::
|
||||
Traversable t =>
|
||||
(a -> b)
|
||||
-> t a
|
||||
-> t b
|
||||
fmapT =
|
||||
error "todo: fmapT"
|
||||
|
||||
-- | Let's refactor out the call to @traverse@ as an argument to @fmapT@.
|
||||
over ::
|
||||
((a -> Identity b) -> s -> Identity t)
|
||||
-> (a -> b)
|
||||
-> s
|
||||
-> t
|
||||
over =
|
||||
error "todo: over"
|
||||
|
||||
-- | Here is @fmapT@ again, passing @traverse@ to @over@.
|
||||
fmapTAgain ::
|
||||
Traversable t =>
|
||||
(a -> b)
|
||||
-> t a
|
||||
-> t b
|
||||
fmapTAgain =
|
||||
error "todo: fmapTAgain"
|
||||
|
||||
-- | Let's create a type-alias for this type of function.
|
||||
type Set s t a b =
|
||||
(a -> Identity b)
|
||||
-> s
|
||||
-> Identity t
|
||||
|
||||
-- | Let's write an inverse to @over@ that does the @Identity@ wrapping &
|
||||
-- unwrapping.
|
||||
sets ::
|
||||
((a -> b) -> s -> t)
|
||||
-> Set s t a b
|
||||
sets =
|
||||
error "todo: sets"
|
||||
|
||||
mapped ::
|
||||
Functor f =>
|
||||
Set (f a) (f b) a b
|
||||
mapped =
|
||||
error "todo: mapped"
|
||||
|
||||
set ::
|
||||
Set s t a b
|
||||
-> s
|
||||
-> b
|
||||
-> t
|
||||
set =
|
||||
error "todo: set"
|
||||
|
||||
----
|
||||
|
||||
-- | Observe that @fmap@ can be recovered from @traverse@ using @Identity@.
|
||||
--
|
||||
-- /Reminder:/ foldMap :: (Foldable t, Monoid b) => (a -> b) -> t a -> b
|
||||
foldMapT ::
|
||||
(Traversable t, Monoid b) =>
|
||||
(a -> b)
|
||||
-> t a
|
||||
-> b
|
||||
foldMapT =
|
||||
error "todo: foldMapT"
|
||||
|
||||
-- | Let's refactor out the call to @traverse@ as an argument to @foldMapT@.
|
||||
foldMapOf ::
|
||||
((a -> Const r b) -> s -> Const r t)
|
||||
-> (a -> r)
|
||||
-> s
|
||||
-> r
|
||||
foldMapOf =
|
||||
error "todo: foldMapOf"
|
||||
|
||||
-- | Here is @foldMapT@ again, passing @traverse@ to @foldMapOf@.
|
||||
foldMapTAgain ::
|
||||
(Traversable t, Monoid b) =>
|
||||
(a -> b)
|
||||
-> t a
|
||||
-> b
|
||||
foldMapTAgain =
|
||||
error "todo: foldMapTAgain"
|
||||
|
||||
-- | Let's create a type-alias for this type of function.
|
||||
type Fold s t a b =
|
||||
forall r.
|
||||
Monoid r =>
|
||||
(a -> Const r b)
|
||||
-> s
|
||||
-> Const r t
|
||||
|
||||
-- | Let's write an inverse to @foldMapOf@ that does the @Const@ wrapping &
|
||||
-- unwrapping.
|
||||
folds ::
|
||||
((a -> b) -> s -> t)
|
||||
-> (a -> Const b a)
|
||||
-> s
|
||||
-> Const t s
|
||||
folds =
|
||||
error "todo: folds"
|
||||
|
||||
folded ::
|
||||
Foldable f =>
|
||||
Fold (f a) (f a) a a
|
||||
folded =
|
||||
error "todo: folded"
|
||||
|
||||
----
|
||||
|
||||
-- | @Get@ is like @Fold@, but without the @Monoid@ constraint.
|
||||
type Get r s a =
|
||||
(a -> Const r a)
|
||||
-> s
|
||||
-> Const r s
|
||||
|
||||
get ::
|
||||
Get a s a
|
||||
-> s
|
||||
-> a
|
||||
get =
|
||||
error "todo: get"
|
||||
|
||||
----
|
||||
|
||||
-- | Let's generalise @Identity@ and @Const r@ to any @Applicative@ instance.
|
||||
type Traversal s t a b =
|
||||
forall f.
|
||||
Applicative f =>
|
||||
(a -> f b)
|
||||
-> s
|
||||
-> f t
|
||||
|
||||
-- | Traverse both sides of a pair.
|
||||
both ::
|
||||
Traversal (a, a) (b, b) a b
|
||||
both =
|
||||
error "todo: both"
|
||||
|
||||
-- | Traverse the left side of @Either@.
|
||||
traverseLeft ::
|
||||
Traversal (Either a x) (Either b x) a b
|
||||
traverseLeft =
|
||||
error "todo: traverseLeft"
|
||||
|
||||
-- | Traverse the right side of @Either@.
|
||||
traverseRight ::
|
||||
Traversal (Either x a) (Either x b) a b
|
||||
traverseRight =
|
||||
error "todo: traverseRight"
|
||||
|
||||
type Traversal' a b =
|
||||
Traversal a a b b
|
||||
|
||||
----
|
||||
|
||||
-- | @Const r@ is @Applicative@, if @Monoid r@, however, without the @Monoid@
|
||||
-- constraint (as in @Get@), the only shared abstraction between @Identity@ and
|
||||
-- @Const r@ is @Functor@.
|
||||
--
|
||||
-- Consequently, we arrive at our lens derivation:
|
||||
type Lens s t a b =
|
||||
forall f.
|
||||
Functor f =>
|
||||
(a -> f b)
|
||||
-> s
|
||||
-> f t
|
||||
|
||||
----
|
||||
|
||||
-- | A prism is a less specific type of traversal.
|
||||
type Prism s t a b =
|
||||
forall p f.
|
||||
(Choice p, Applicative f) =>
|
||||
p a (f b)
|
||||
-> p s (f t)
|
||||
|
||||
_Left ::
|
||||
Prism (Either a x) (Either b x) a b
|
||||
_Left =
|
||||
error "todo: _Left"
|
||||
|
||||
_Right ::
|
||||
Prism (Either x a) (Either x b) a b
|
||||
_Right =
|
||||
error "todo: _Right"
|
||||
|
||||
prism ::
|
||||
(b -> t)
|
||||
-> (s -> Either t a)
|
||||
-> Prism s t a b
|
||||
prism =
|
||||
error "todo: prism"
|
||||
|
||||
_Just ::
|
||||
Prism (Maybe a) (Maybe b) a b
|
||||
_Just =
|
||||
error "todo: _Just"
|
||||
|
||||
_Nothing ::
|
||||
Prism (Maybe a) (Maybe a) () ()
|
||||
_Nothing =
|
||||
error "todo: _Nothing"
|
||||
|
||||
setP ::
|
||||
Prism s t a b
|
||||
-> s
|
||||
-> Either t a
|
||||
setP =
|
||||
error "todo: setP"
|
||||
|
||||
getP ::
|
||||
Prism s t a b
|
||||
-> b
|
||||
-> t
|
||||
getP =
|
||||
error "todo: getP"
|
||||
|
||||
type Prism' a b =
|
||||
Prism a a b b
|
||||
|
||||
----
|
||||
|
||||
-- |
|
||||
--
|
||||
-- >>> modify fstL (+1) (0 :: Int, "abc")
|
||||
-- (1,"abc")
|
||||
--
|
||||
-- >>> modify sndL (+1) ("abc", 0 :: Int)
|
||||
-- ("abc",1)
|
||||
--
|
||||
-- prop> let types = (x :: Int, y :: String) in modify fstL id (x, y) == (x, y)
|
||||
--
|
||||
-- prop> let types = (x :: Int, y :: String) in modify sndL id (x, y) == (x, y)
|
||||
modify ::
|
||||
Lens s t a b
|
||||
-> (a -> b)
|
||||
-> s
|
||||
-> t
|
||||
modify =
|
||||
error "todo: modify"
|
||||
|
||||
-- | An alias for @modify@.
|
||||
(%~) ::
|
||||
Lens s t a b
|
||||
-> (a -> b)
|
||||
-> s
|
||||
-> t
|
||||
(%~) =
|
||||
modify
|
||||
|
||||
infixr 4 %~
|
||||
|
||||
-- |
|
||||
--
|
||||
-- >>> fstL .~ 1 $ (0 :: Int, "abc")
|
||||
-- (1,"abc")
|
||||
--
|
||||
-- >>> sndL .~ 1 $ ("abc", 0 :: Int)
|
||||
-- ("abc",1)
|
||||
--
|
||||
-- prop> let types = (x :: Int, y :: String) in set fstL (x, y) z == (fstL .~ z $ (x, y))
|
||||
--
|
||||
-- prop> let types = (x :: Int, y :: String) in set sndL (x, y) z == (sndL .~ z $ (x, y))
|
||||
(.~) ::
|
||||
Lens s t a b
|
||||
-> b
|
||||
-> s
|
||||
-> t
|
||||
(.~) =
|
||||
error "todo: (.~)"
|
||||
|
||||
infixl 5 .~
|
||||
|
||||
-- |
|
||||
--
|
||||
-- >>> fmodify fstL (+) (5 :: Int, "abc") 8
|
||||
-- (13,"abc")
|
||||
--
|
||||
-- >>> fmodify fstL (\n -> bool Nothing (Just (n * 2)) (even n)) (10, "abc")
|
||||
-- Just (20,"abc")
|
||||
--
|
||||
-- >>> fmodify fstL (\n -> bool Nothing (Just (n * 2)) (even n)) (11, "abc")
|
||||
-- Nothing
|
||||
fmodify ::
|
||||
Functor f =>
|
||||
Lens s t a b
|
||||
-> (a -> f b)
|
||||
-> s
|
||||
-> f t
|
||||
fmodify =
|
||||
error "todo: fmodify"
|
||||
|
||||
-- |
|
||||
--
|
||||
-- >>> fstL |= Just 3 $ (7, "abc")
|
||||
-- Just (3,"abc")
|
||||
--
|
||||
-- >>> (fstL |= (+1) $ (3, "abc")) 17
|
||||
-- (18,"abc")
|
||||
(|=) ::
|
||||
Functor f =>
|
||||
Lens s t a b
|
||||
-> f b
|
||||
-> s
|
||||
-> f t
|
||||
(|=) =
|
||||
error "todo: (|=)"
|
||||
|
||||
infixl 5 |=
|
||||
|
||||
-- |
|
||||
--
|
||||
-- >>> modify fstL (*10) (3, "abc")
|
||||
-- (30,"abc")
|
||||
fstL ::
|
||||
Lens (a, x) (b, x) a b
|
||||
fstL =
|
||||
error "todo: fstL"
|
||||
|
||||
-- |
|
||||
--
|
||||
-- >>> modify sndL (++ "def") (13, "abc")
|
||||
-- (13,"abcdef")
|
||||
sndL ::
|
||||
Lens (x, a) (x, b) a b
|
||||
sndL =
|
||||
error "todo: sndL"
|
||||
|
||||
-- |
|
||||
--
|
||||
-- >>> get (mapL 3) (Map.fromList (map (\c -> (ord c - 96, c)) ['a'..'d']))
|
||||
-- Just 'c'
|
||||
--
|
||||
-- >>> get (mapL 33) (Map.fromList (map (\c -> (ord c - 96, c)) ['a'..'d']))
|
||||
-- Nothing
|
||||
--
|
||||
-- >>> set (mapL 3) (Map.fromList (map (\c -> (ord c - 96, c)) ['a'..'d'])) (Just 'X')
|
||||
-- fromList [(1,'a'),(2,'b'),(3,'X'),(4,'d')]
|
||||
--
|
||||
-- >>> set (mapL 33) (Map.fromList (map (\c -> (ord c - 96, c)) ['a'..'d'])) (Just 'X')
|
||||
-- fromList [(1,'a'),(2,'b'),(3,'c'),(4,'d'),(33,'X')]
|
||||
--
|
||||
-- >>> set (mapL 3) (Map.fromList (map (\c -> (ord c - 96, c)) ['a'..'d'])) Nothing
|
||||
-- fromList [(1,'a'),(2,'b'),(4,'d')]
|
||||
--
|
||||
-- >>> set (mapL 33) (Map.fromList (map (\c -> (ord c - 96, c)) ['a'..'d'])) Nothing
|
||||
-- fromList [(1,'a'),(2,'b'),(3,'c'),(4,'d')]
|
||||
mapL ::
|
||||
Ord k =>
|
||||
k
|
||||
-> Lens (Map k v) (Map k v) (Maybe v) (Maybe v)
|
||||
mapL =
|
||||
error "todo: mapL"
|
||||
|
||||
-- |
|
||||
--
|
||||
-- >>> get (setL 3) (Set.fromList [1..5])
|
||||
-- True
|
||||
--
|
||||
-- >>> get (setL 33) (Set.fromList [1..5])
|
||||
-- False
|
||||
--
|
||||
-- >>> set (setL 3) (Set.fromList [1..5]) True
|
||||
-- fromList [1,2,3,4,5]
|
||||
--
|
||||
-- >>> set (setL 3) (Set.fromList [1..5]) False
|
||||
-- fromList [1,2,4,5]
|
||||
--
|
||||
-- >>> set (setL 33) (Set.fromList [1..5]) True
|
||||
-- fromList [1,2,3,4,5,33]
|
||||
--
|
||||
-- >>> set (setL 33) (Set.fromList [1..5]) False
|
||||
-- fromList [1,2,3,4,5]
|
||||
setL ::
|
||||
Ord k =>
|
||||
k
|
||||
-> Lens (Set.Set k) (Set.Set k) Bool Bool
|
||||
setL =
|
||||
error "todo: setL"
|
||||
|
||||
-- |
|
||||
--
|
||||
-- >>> get (compose fstL sndL) ("abc", (7, "def"))
|
||||
-- 7
|
||||
--
|
||||
-- >>> set (compose fstL sndL) ("abc", (7, "def")) 8
|
||||
-- ("abc",(8,"def"))
|
||||
compose ::
|
||||
Lens s t a b
|
||||
-> Lens q r s t
|
||||
-> Lens q r a b
|
||||
compose =
|
||||
error "todo: compose"
|
||||
|
||||
-- | An alias for @compose@.
|
||||
(|.) ::
|
||||
Lens s t a b
|
||||
-> Lens q r s t
|
||||
-> Lens q r a b
|
||||
(|.) =
|
||||
compose
|
||||
|
||||
infixr 9 |.
|
||||
|
||||
-- |
|
||||
--
|
||||
-- >>> get identity 3
|
||||
-- 3
|
||||
--
|
||||
-- >>> set identity 3 4
|
||||
-- 4
|
||||
identity ::
|
||||
Lens a b a b
|
||||
identity =
|
||||
error "todo: identity"
|
||||
|
||||
-- |
|
||||
--
|
||||
-- >>> get (product fstL sndL) (("abc", 3), (4, "def"))
|
||||
-- ("abc","def")
|
||||
--
|
||||
-- >>> set (product fstL sndL) (("abc", 3), (4, "def")) ("ghi", "jkl")
|
||||
-- (("ghi",3),(4,"jkl"))
|
||||
product ::
|
||||
Lens s t a b
|
||||
-> Lens q r c d
|
||||
-> Lens (s, q) (t, r) (a, c) (b, d)
|
||||
product =
|
||||
error "todo: product"
|
||||
|
||||
-- | An alias for @product@.
|
||||
(***) ::
|
||||
Lens s t a b
|
||||
-> Lens q r c d
|
||||
-> Lens (s, q) (t, r) (a, c) (b, d)
|
||||
(***) =
|
||||
product
|
||||
|
||||
infixr 3 ***
|
||||
|
||||
-- |
|
||||
--
|
||||
-- >>> get (choice fstL sndL) (Left ("abc", 7))
|
||||
-- "abc"
|
||||
--
|
||||
-- >>> get (choice fstL sndL) (Right ("abc", 7))
|
||||
-- 7
|
||||
--
|
||||
-- >>> set (choice fstL sndL) (Left ("abc", 7)) "def"
|
||||
-- Left ("def",7)
|
||||
--
|
||||
-- >>> set (choice fstL sndL) (Right ("abc", 7)) 8
|
||||
-- Right ("abc",8)
|
||||
choice ::
|
||||
Lens s t a b
|
||||
-> Lens q r a b
|
||||
-> Lens (Either s q) (Either t r) a b
|
||||
choice =
|
||||
error "todo: choice"
|
||||
|
||||
-- | An alias for @choice@.
|
||||
(|||) ::
|
||||
Lens s t a b
|
||||
-> Lens q r a b
|
||||
-> Lens (Either s q) (Either t r) a b
|
||||
(|||) =
|
||||
choice
|
||||
|
||||
infixr 2 |||
|
||||
|
||||
----
|
||||
|
||||
type Lens' a b =
|
||||
Lens a a b b
|
||||
|
||||
cityL ::
|
||||
Lens' Locality String
|
||||
cityL p (Locality c t y) =
|
||||
fmap (\c' -> Locality c' t y) (p c)
|
||||
|
||||
stateL ::
|
||||
Lens' Locality String
|
||||
stateL p (Locality c t y) =
|
||||
fmap (\t' -> Locality c t' y) (p t)
|
||||
|
||||
countryL ::
|
||||
Lens' Locality String
|
||||
countryL p (Locality c t y) =
|
||||
fmap (\y' -> Locality c t y') (p y)
|
||||
|
||||
streetL ::
|
||||
Lens' Address String
|
||||
streetL p (Address t s l) =
|
||||
fmap (\t' -> Address t' s l) (p t)
|
||||
|
||||
suburbL ::
|
||||
Lens' Address String
|
||||
suburbL p (Address t s l) =
|
||||
fmap (\s' -> Address t s' l) (p s)
|
||||
|
||||
localityL ::
|
||||
Lens' Address Locality
|
||||
localityL p (Address t s l) =
|
||||
fmap (\l' -> Address t s l') (p l)
|
||||
|
||||
ageL ::
|
||||
Lens' Person Int
|
||||
ageL p (Person a n d) =
|
||||
fmap (\a' -> Person a' n d) (p a)
|
||||
|
||||
nameL ::
|
||||
Lens' Person String
|
||||
nameL p (Person a n d) =
|
||||
fmap (\n' -> Person a n' d) (p n)
|
||||
|
||||
addressL ::
|
||||
Lens' Person Address
|
||||
addressL p (Person a n d) =
|
||||
fmap (\d' -> Person a n d') (p d)
|
||||
|
||||
intAndIntL ::
|
||||
Lens' (IntAnd a) Int
|
||||
intAndIntL p (IntAnd n a) =
|
||||
fmap (\n' -> IntAnd n' a) (p n)
|
||||
|
||||
-- lens for polymorphic update
|
||||
intAndL ::
|
||||
Lens (IntAnd a) (IntAnd b) a b
|
||||
intAndL p (IntAnd n a) =
|
||||
fmap (\a' -> IntAnd n a') (p a)
|
||||
|
||||
-- |
|
||||
--
|
||||
-- >>> get (suburbL |. addressL) fred
|
||||
-- "Fredville"
|
||||
--
|
||||
-- >>> get (suburbL |. addressL) mary
|
||||
-- "Maryland"
|
||||
getSuburb ::
|
||||
Person
|
||||
-> String
|
||||
getSuburb =
|
||||
error "todo: getSuburb"
|
||||
|
||||
-- |
|
||||
--
|
||||
-- >>> setStreet fred "Some Other St"
|
||||
-- Person 24 "Fred" (Address "Some Other St" "Fredville" (Locality "Fredmania" "New South Fred" "Fredalia"))
|
||||
--
|
||||
-- >>> setStreet mary "Some Other St"
|
||||
-- Person 28 "Mary" (Address "Some Other St" "Maryland" (Locality "Mary Mary" "Western Mary" "Maristan"))
|
||||
setStreet ::
|
||||
Person
|
||||
-> String
|
||||
-> Person
|
||||
setStreet =
|
||||
error "todo: setStreet"
|
||||
|
||||
-- |
|
||||
--
|
||||
-- >>> getAgeAndCountry (fred, maryLocality)
|
||||
-- (24,"Maristan")
|
||||
--
|
||||
-- >>> getAgeAndCountry (mary, fredLocality)
|
||||
-- (28,"Fredalia")
|
||||
getAgeAndCountry ::
|
||||
(Person, Locality)
|
||||
-> (Int, String)
|
||||
getAgeAndCountry =
|
||||
error "todo: getAgeAndCountry"
|
||||
|
||||
-- |
|
||||
--
|
||||
-- >>> setCityAndLocality (fred, maryAddress) ("Some Other City", fredLocality)
|
||||
-- (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"))
|
||||
--
|
||||
-- >>> setCityAndLocality (mary, fredAddress) ("Some Other City", maryLocality)
|
||||
-- (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"))
|
||||
setCityAndLocality ::
|
||||
(Person, Address) -> (String, Locality) -> (Person, Address)
|
||||
setCityAndLocality =
|
||||
error "todo: setCityAndLocality"
|
||||
|
||||
-- |
|
||||
--
|
||||
-- >>> getSuburbOrCity (Left maryAddress)
|
||||
-- "Maryland"
|
||||
--
|
||||
-- >>> getSuburbOrCity (Right fredLocality)
|
||||
-- "Fredmania"
|
||||
getSuburbOrCity ::
|
||||
Either Address Locality
|
||||
-> String
|
||||
getSuburbOrCity =
|
||||
error "todo: getSuburbOrCity"
|
||||
|
||||
-- |
|
||||
--
|
||||
-- >>> setStreetOrState (Right maryLocality) "Some Other State"
|
||||
-- Right (Locality "Mary Mary" "Some Other State" "Maristan")
|
||||
--
|
||||
-- >>> setStreetOrState (Left fred) "Some Other St"
|
||||
-- Left (Person 24 "Fred" (Address "Some Other St" "Fredville" (Locality "Fredmania" "New South Fred" "Fredalia")))
|
||||
setStreetOrState ::
|
||||
Either Person Locality
|
||||
-> String
|
||||
-> Either Person Locality
|
||||
setStreetOrState =
|
||||
error "todo: setStreetOrState"
|
||||
|
||||
-- |
|
||||
--
|
||||
-- >>> modifyCityUppercase fred
|
||||
-- Person 24 "Fred" (Address "15 Fred St" "Fredville" (Locality "FREDMANIA" "New South Fred" "Fredalia"))
|
||||
--
|
||||
-- >>> modifyCityUppercase mary
|
||||
-- Person 28 "Mary" (Address "83 Mary Ln" "Maryland" (Locality "MARY MARY" "Western Mary" "Maristan"))
|
||||
modifyCityUppercase ::
|
||||
Person
|
||||
-> Person
|
||||
modifyCityUppercase =
|
||||
error "todo: modifyCityUppercase"
|
||||
|
||||
-- |
|
||||
--
|
||||
-- >>> modifyIntAndLengthEven (IntAnd 10 "abc")
|
||||
-- IntAnd 10 False
|
||||
--
|
||||
-- >>> modifyIntAndLengthEven (IntAnd 10 "abcd")
|
||||
-- IntAnd 10 True
|
||||
modifyIntAndLengthEven ::
|
||||
IntAnd [a]
|
||||
-> IntAnd Bool
|
||||
modifyIntAndLengthEven =
|
||||
error "todo: modifyIntAndLengthEven"
|
||||
|
||||
----
|
||||
|
||||
-- |
|
||||
--
|
||||
-- >>> over traverseLocality (map toUpper) (Locality "abc" "def" "ghi")
|
||||
-- Locality "ABC" "DEF" "GHI"
|
||||
traverseLocality ::
|
||||
Traversal' Locality String
|
||||
traverseLocality =
|
||||
error "todo: traverseLocality"
|
||||
|
||||
-- |
|
||||
--
|
||||
-- >>> over intOrIntP (*10) (IntOrIs 3)
|
||||
-- IntOrIs 30
|
||||
--
|
||||
-- >>> over intOrIntP (*10) (IntOrIsNot "abc")
|
||||
-- IntOrIsNot "abc"
|
||||
intOrIntP ::
|
||||
Prism' (IntOr a) Int
|
||||
intOrIntP =
|
||||
error "todo: intOrIntP"
|
||||
|
||||
intOrP ::
|
||||
Prism (IntOr a) (IntOr b) a b
|
||||
intOrP =
|
||||
error "todo: intOrP"
|
||||
|
||||
-- |
|
||||
--
|
||||
-- >> over intOrP (even . length) (IntOrIsNot "abc")
|
||||
-- IntOrIsNot False
|
||||
--
|
||||
-- >>> over intOrP (even . length) (IntOrIsNot "abcd")
|
||||
-- IntOrIsNot True
|
||||
--
|
||||
-- >>> over intOrP (even . length) (IntOrIs 10)
|
||||
-- IntOrIs 10
|
||||
intOrLengthEven ::
|
||||
IntOr [a]
|
||||
-> IntOr Bool
|
||||
intOrLengthEven =
|
||||
error "todo: intOrLengthEven"
|
||||
|
|
|
|||
|
|
@ -1,788 +0,0 @@
|
|||
{-# LANGUAGE RankNTypes #-}
|
||||
|
||||
module Lets.Lens.Lens (
|
||||
fmapT
|
||||
, over
|
||||
, fmapTAgain
|
||||
, Set
|
||||
, sets
|
||||
, mapped
|
||||
, set
|
||||
, foldMapT
|
||||
, foldMapOf
|
||||
, foldMapTAgain
|
||||
, Fold
|
||||
, folds
|
||||
, folded
|
||||
, Get
|
||||
, get
|
||||
, Traversal
|
||||
, both
|
||||
, traverseLeft
|
||||
, traverseRight
|
||||
, Traversal'
|
||||
, Lens
|
||||
, Prism
|
||||
, _Left
|
||||
, _Right
|
||||
, prism
|
||||
, _Just
|
||||
, _Nothing
|
||||
, setP
|
||||
, getP
|
||||
, Prism'
|
||||
, modify
|
||||
, (%~)
|
||||
, (.~)
|
||||
, fmodify
|
||||
, (|=)
|
||||
, fstL
|
||||
, sndL
|
||||
, mapL
|
||||
, setL
|
||||
, compose
|
||||
, (|.)
|
||||
, identity
|
||||
, product
|
||||
, (***)
|
||||
, choice
|
||||
, (|||)
|
||||
, Lens'
|
||||
, cityL
|
||||
, stateL
|
||||
, countryL
|
||||
, streetL
|
||||
, suburbL
|
||||
, localityL
|
||||
, ageL
|
||||
, nameL
|
||||
, addressL
|
||||
, intAndIntL
|
||||
, intAndL
|
||||
, getSuburb
|
||||
, setStreet
|
||||
, getAgeAndCountry
|
||||
, setCityAndLocality
|
||||
, getSuburbOrCity
|
||||
, setStreetOrState
|
||||
, modifyCityUppercase
|
||||
, modifyIntAndLengthEven
|
||||
, traverseLocality
|
||||
, intOrIntP
|
||||
, intOrP
|
||||
, intOrLengthEven
|
||||
) where
|
||||
|
||||
import Control.Applicative(Applicative((<*>), pure))
|
||||
import Data.Bool(bool)
|
||||
import Data.Char(toUpper)
|
||||
import Data.Foldable(Foldable(foldMap))
|
||||
import Data.Functor((<$>))
|
||||
import Data.Map(Map)
|
||||
import qualified Data.Map as Map(insert, delete, lookup)
|
||||
import Data.Monoid(Monoid)
|
||||
import qualified Data.Set as Set(Set, insert, delete, member)
|
||||
import Data.Traversable(Traversable(traverse))
|
||||
import Lets.Data(AlongsideLeft(AlongsideLeft, getAlongsideLeft), AlongsideRight(AlongsideRight, getAlongsideRight), Identity(Identity, getIdentity), Const(Const, getConst), Tagged(Tagged, getTagged), IntOr(IntOrIs, IntOrIsNot), IntAnd(IntAnd), Person(Person), Locality(Locality), Address(Address))
|
||||
import Lets.Lens.Choice(Choice(left, right))
|
||||
import Lets.Lens.Profunctor(Profunctor(dimap))
|
||||
import Prelude hiding (product)
|
||||
|
||||
-- $setup
|
||||
-- >>> import qualified Data.Map as Map(fromList)
|
||||
-- >>> import qualified Data.Set as Set(fromList)
|
||||
-- >>> import Data.Char(ord)
|
||||
|
||||
-- Let's remind ourselves of Traversable, noting Foldable and Functor.
|
||||
--
|
||||
-- class (Foldable t, Functor t) => Traversable t where
|
||||
-- traverse ::
|
||||
-- Applicative f =>
|
||||
-- (a -> f b)
|
||||
-- -> t a
|
||||
-- -> f (t b)
|
||||
|
||||
-- | Observe that @fmap@ can be recovered from @traverse@ using @Identity@.
|
||||
--
|
||||
-- /Reminder:/ fmap :: Functor t => (a -> b) -> t a -> t b
|
||||
fmapT ::
|
||||
Traversable t =>
|
||||
(a -> b)
|
||||
-> t a
|
||||
-> t b
|
||||
fmapT =
|
||||
error "todo: fmapT"
|
||||
|
||||
-- | Let's refactor out the call to @traverse@ as an argument to @fmapT@.
|
||||
over ::
|
||||
((a -> Identity b) -> s -> Identity t)
|
||||
-> (a -> b)
|
||||
-> s
|
||||
-> t
|
||||
over =
|
||||
error "todo: over"
|
||||
|
||||
-- | Here is @fmapT@ again, passing @traverse@ to @over@.
|
||||
fmapTAgain ::
|
||||
Traversable t =>
|
||||
(a -> b)
|
||||
-> t a
|
||||
-> t b
|
||||
fmapTAgain =
|
||||
error "todo: fmapTAgain"
|
||||
|
||||
-- | Let's create a type-alias for this type of function.
|
||||
type Set s t a b =
|
||||
(a -> Identity b)
|
||||
-> s
|
||||
-> Identity t
|
||||
|
||||
-- | Let's write an inverse to @over@ that does the @Identity@ wrapping &
|
||||
-- unwrapping.
|
||||
sets ::
|
||||
((a -> b) -> s -> t)
|
||||
-> Set s t a b
|
||||
sets =
|
||||
error "todo: sets"
|
||||
|
||||
mapped ::
|
||||
Functor f =>
|
||||
Set (f a) (f b) a b
|
||||
mapped =
|
||||
error "todo: mapped"
|
||||
|
||||
set ::
|
||||
Set s t a b
|
||||
-> s
|
||||
-> b
|
||||
-> t
|
||||
set =
|
||||
error "todo: set"
|
||||
|
||||
----
|
||||
|
||||
-- | Observe that @fmap@ can be recovered from @traverse@ using @Identity@.
|
||||
--
|
||||
-- /Reminder:/ foldMap :: (Foldable t, Monoid b) => (a -> b) -> t a -> b
|
||||
foldMapT ::
|
||||
(Traversable t, Monoid b) =>
|
||||
(a -> b)
|
||||
-> t a
|
||||
-> b
|
||||
foldMapT =
|
||||
error "todo: foldMapT"
|
||||
|
||||
-- | Let's refactor out the call to @traverse@ as an argument to @foldMapT@.
|
||||
foldMapOf ::
|
||||
((a -> Const r b) -> s -> Const r t)
|
||||
-> (a -> r)
|
||||
-> s
|
||||
-> r
|
||||
foldMapOf =
|
||||
error "todo: foldMapOf"
|
||||
|
||||
-- | Here is @foldMapT@ again, passing @traverse@ to @foldMapOf@.
|
||||
foldMapTAgain ::
|
||||
(Traversable t, Monoid b) =>
|
||||
(a -> b)
|
||||
-> t a
|
||||
-> b
|
||||
foldMapTAgain =
|
||||
error "todo: foldMapTAgain"
|
||||
|
||||
-- | Let's create a type-alias for this type of function.
|
||||
type Fold s t a b =
|
||||
forall r.
|
||||
Monoid r =>
|
||||
(a -> Const r b)
|
||||
-> s
|
||||
-> Const r t
|
||||
|
||||
-- | Let's write an inverse to @foldMapOf@ that does the @Const@ wrapping &
|
||||
-- unwrapping.
|
||||
folds ::
|
||||
((a -> b) -> s -> t)
|
||||
-> (a -> Const b a)
|
||||
-> s
|
||||
-> Const t s
|
||||
folds =
|
||||
error "todo: folds"
|
||||
|
||||
folded ::
|
||||
Foldable f =>
|
||||
Fold (f a) (f a) a a
|
||||
folded =
|
||||
error "todo: folded"
|
||||
|
||||
----
|
||||
|
||||
-- | @Get@ is like @Fold@, but without the @Monoid@ constraint.
|
||||
type Get r s a =
|
||||
(a -> Const r a)
|
||||
-> s
|
||||
-> Const r s
|
||||
|
||||
get ::
|
||||
Get a s a
|
||||
-> s
|
||||
-> a
|
||||
get =
|
||||
error "todo: get"
|
||||
|
||||
----
|
||||
|
||||
-- | Let's generalise @Identity@ and @Const r@ to any @Applicative@ instance.
|
||||
type Traversal s t a b =
|
||||
forall f.
|
||||
Applicative f =>
|
||||
(a -> f b)
|
||||
-> s
|
||||
-> f t
|
||||
|
||||
-- | Traverse both sides of a pair.
|
||||
both ::
|
||||
Traversal (a, a) (b, b) a b
|
||||
both =
|
||||
error "todo: both"
|
||||
|
||||
-- | Traverse the left side of @Either@.
|
||||
traverseLeft ::
|
||||
Traversal (Either a x) (Either b x) a b
|
||||
traverseLeft =
|
||||
error "todo: traverseLeft"
|
||||
|
||||
-- | Traverse the right side of @Either@.
|
||||
traverseRight ::
|
||||
Traversal (Either x a) (Either x b) a b
|
||||
traverseRight =
|
||||
error "todo: traverseRight"
|
||||
|
||||
type Traversal' a b =
|
||||
Traversal a a b b
|
||||
|
||||
----
|
||||
|
||||
-- | @Const r@ is @Applicative@, if @Monoid r@, however, without the @Monoid@
|
||||
-- constraint (as in @Get@), the only shared abstraction between @Identity@ and
|
||||
-- @Const r@ is @Functor@.
|
||||
--
|
||||
-- Consequently, we arrive at our lens derivation:
|
||||
type Lens s t a b =
|
||||
forall f.
|
||||
Functor f =>
|
||||
(a -> f b)
|
||||
-> s
|
||||
-> f t
|
||||
|
||||
----
|
||||
|
||||
-- | A prism is a less specific type of traversal.
|
||||
type Prism s t a b =
|
||||
forall p f.
|
||||
(Choice p, Applicative f) =>
|
||||
p a (f b)
|
||||
-> p s (f t)
|
||||
|
||||
_Left ::
|
||||
Prism (Either a x) (Either b x) a b
|
||||
_Left =
|
||||
error "todo: _Left"
|
||||
|
||||
_Right ::
|
||||
Prism (Either x a) (Either x b) a b
|
||||
_Right =
|
||||
error "todo: _Right"
|
||||
|
||||
prism ::
|
||||
(b -> t)
|
||||
-> (s -> Either t a)
|
||||
-> Prism s t a b
|
||||
prism =
|
||||
error "todo: prism"
|
||||
|
||||
_Just ::
|
||||
Prism (Maybe a) (Maybe b) a b
|
||||
_Just =
|
||||
error "todo: _Just"
|
||||
|
||||
_Nothing ::
|
||||
Prism (Maybe a) (Maybe a) () ()
|
||||
_Nothing =
|
||||
error "todo: _Nothing"
|
||||
|
||||
setP ::
|
||||
Prism s t a b
|
||||
-> s
|
||||
-> Either t a
|
||||
setP =
|
||||
error "todo: setP"
|
||||
|
||||
getP ::
|
||||
Prism s t a b
|
||||
-> b
|
||||
-> t
|
||||
getP =
|
||||
error "todo: getP"
|
||||
|
||||
type Prism' a b =
|
||||
Prism a a b b
|
||||
|
||||
----
|
||||
|
||||
-- |
|
||||
--
|
||||
-- >>> modify fstL (+1) (0 :: Int, "abc")
|
||||
-- (1,"abc")
|
||||
--
|
||||
-- >>> modify sndL (+1) ("abc", 0 :: Int)
|
||||
-- ("abc",1)
|
||||
--
|
||||
-- prop> let types = (x :: Int, y :: String) in modify fstL id (x, y) == (x, y)
|
||||
--
|
||||
-- prop> let types = (x :: Int, y :: String) in modify sndL id (x, y) == (x, y)
|
||||
modify ::
|
||||
Lens s t a b
|
||||
-> (a -> b)
|
||||
-> s
|
||||
-> t
|
||||
modify =
|
||||
error "todo: modify"
|
||||
|
||||
-- | An alias for @modify@.
|
||||
(%~) ::
|
||||
Lens s t a b
|
||||
-> (a -> b)
|
||||
-> s
|
||||
-> t
|
||||
(%~) =
|
||||
modify
|
||||
|
||||
infixr 4 %~
|
||||
|
||||
-- |
|
||||
--
|
||||
-- >>> fstL .~ 1 $ (0 :: Int, "abc")
|
||||
-- (1,"abc")
|
||||
--
|
||||
-- >>> sndL .~ 1 $ ("abc", 0 :: Int)
|
||||
-- ("abc",1)
|
||||
--
|
||||
-- prop> let types = (x :: Int, y :: String) in set fstL (x, y) z == (fstL .~ z $ (x, y))
|
||||
--
|
||||
-- prop> let types = (x :: Int, y :: String) in set sndL (x, y) z == (sndL .~ z $ (x, y))
|
||||
(.~) ::
|
||||
Lens s t a b
|
||||
-> b
|
||||
-> s
|
||||
-> t
|
||||
(.~) =
|
||||
error "todo: (.~)"
|
||||
|
||||
infixl 5 .~
|
||||
|
||||
-- |
|
||||
--
|
||||
-- >>> fmodify fstL (+) (5 :: Int, "abc") 8
|
||||
-- (13,"abc")
|
||||
--
|
||||
-- >>> fmodify fstL (\n -> bool Nothing (Just (n * 2)) (even n)) (10, "abc")
|
||||
-- Just (20,"abc")
|
||||
--
|
||||
-- >>> fmodify fstL (\n -> bool Nothing (Just (n * 2)) (even n)) (11, "abc")
|
||||
-- Nothing
|
||||
fmodify ::
|
||||
Functor f =>
|
||||
Lens s t a b
|
||||
-> (a -> f b)
|
||||
-> s
|
||||
-> f t
|
||||
fmodify =
|
||||
error "todo: fmodify"
|
||||
|
||||
-- |
|
||||
--
|
||||
-- >>> fstL |= Just 3 $ (7, "abc")
|
||||
-- Just (3,"abc")
|
||||
--
|
||||
-- >>> (fstL |= (+1) $ (3, "abc")) 17
|
||||
-- (18,"abc")
|
||||
(|=) ::
|
||||
Functor f =>
|
||||
Lens s t a b
|
||||
-> f b
|
||||
-> s
|
||||
-> f t
|
||||
(|=) =
|
||||
error "todo: (|=)"
|
||||
|
||||
infixl 5 |=
|
||||
|
||||
-- |
|
||||
--
|
||||
-- >>> modify fstL (*10) (3, "abc")
|
||||
-- (30,"abc")
|
||||
fstL ::
|
||||
Lens (a, x) (b, x) a b
|
||||
fstL =
|
||||
error "todo: fstL"
|
||||
|
||||
-- |
|
||||
--
|
||||
-- >>> modify sndL (++ "def") (13, "abc")
|
||||
-- (13,"abcdef")
|
||||
sndL ::
|
||||
Lens (x, a) (x, b) a b
|
||||
sndL =
|
||||
error "todo: sndL"
|
||||
|
||||
-- |
|
||||
--
|
||||
-- >>> get (mapL 3) (Map.fromList (map (\c -> (ord c - 96, c)) ['a'..'d']))
|
||||
-- Just 'c'
|
||||
--
|
||||
-- >>> get (mapL 33) (Map.fromList (map (\c -> (ord c - 96, c)) ['a'..'d']))
|
||||
-- Nothing
|
||||
--
|
||||
-- >>> set (mapL 3) (Map.fromList (map (\c -> (ord c - 96, c)) ['a'..'d'])) (Just 'X')
|
||||
-- fromList [(1,'a'),(2,'b'),(3,'X'),(4,'d')]
|
||||
--
|
||||
-- >>> set (mapL 33) (Map.fromList (map (\c -> (ord c - 96, c)) ['a'..'d'])) (Just 'X')
|
||||
-- fromList [(1,'a'),(2,'b'),(3,'c'),(4,'d'),(33,'X')]
|
||||
--
|
||||
-- >>> set (mapL 3) (Map.fromList (map (\c -> (ord c - 96, c)) ['a'..'d'])) Nothing
|
||||
-- fromList [(1,'a'),(2,'b'),(4,'d')]
|
||||
--
|
||||
-- >>> set (mapL 33) (Map.fromList (map (\c -> (ord c - 96, c)) ['a'..'d'])) Nothing
|
||||
-- fromList [(1,'a'),(2,'b'),(3,'c'),(4,'d')]
|
||||
mapL ::
|
||||
Ord k =>
|
||||
k
|
||||
-> Lens (Map k v) (Map k v) (Maybe v) (Maybe v)
|
||||
mapL =
|
||||
error "todo: mapL"
|
||||
|
||||
-- |
|
||||
--
|
||||
-- >>> get (setL 3) (Set.fromList [1..5])
|
||||
-- True
|
||||
--
|
||||
-- >>> get (setL 33) (Set.fromList [1..5])
|
||||
-- False
|
||||
--
|
||||
-- >>> set (setL 3) (Set.fromList [1..5]) True
|
||||
-- fromList [1,2,3,4,5]
|
||||
--
|
||||
-- >>> set (setL 3) (Set.fromList [1..5]) False
|
||||
-- fromList [1,2,4,5]
|
||||
--
|
||||
-- >>> set (setL 33) (Set.fromList [1..5]) True
|
||||
-- fromList [1,2,3,4,5,33]
|
||||
--
|
||||
-- >>> set (setL 33) (Set.fromList [1..5]) False
|
||||
-- fromList [1,2,3,4,5]
|
||||
setL ::
|
||||
Ord k =>
|
||||
k
|
||||
-> Lens (Set.Set k) (Set.Set k) Bool Bool
|
||||
setL =
|
||||
error "todo: setL"
|
||||
|
||||
-- |
|
||||
--
|
||||
-- >>> get (compose fstL sndL) ("abc", (7, "def"))
|
||||
-- 7
|
||||
--
|
||||
-- >>> set (compose fstL sndL) ("abc", (7, "def")) 8
|
||||
-- ("abc",(8,"def"))
|
||||
compose ::
|
||||
Lens s t a b
|
||||
-> Lens q r s t
|
||||
-> Lens q r a b
|
||||
compose =
|
||||
error "todo: compose"
|
||||
|
||||
-- | An alias for @compose@.
|
||||
(|.) ::
|
||||
Lens s t a b
|
||||
-> Lens q r s t
|
||||
-> Lens q r a b
|
||||
(|.) =
|
||||
compose
|
||||
|
||||
infixr 9 |.
|
||||
|
||||
-- |
|
||||
--
|
||||
-- >>> get identity 3
|
||||
-- 3
|
||||
--
|
||||
-- >>> set identity 3 4
|
||||
-- 4
|
||||
identity ::
|
||||
Lens a b a b
|
||||
identity =
|
||||
error "todo: identity"
|
||||
|
||||
-- |
|
||||
--
|
||||
-- >>> get (product fstL sndL) (("abc", 3), (4, "def"))
|
||||
-- ("abc","def")
|
||||
--
|
||||
-- >>> set (product fstL sndL) (("abc", 3), (4, "def")) ("ghi", "jkl")
|
||||
-- (("ghi",3),(4,"jkl"))
|
||||
product ::
|
||||
Lens s t a b
|
||||
-> Lens q r c d
|
||||
-> Lens (s, q) (t, r) (a, c) (b, d)
|
||||
product =
|
||||
error "todo: product"
|
||||
|
||||
-- | An alias for @product@.
|
||||
(***) ::
|
||||
Lens s t a b
|
||||
-> Lens q r c d
|
||||
-> Lens (s, q) (t, r) (a, c) (b, d)
|
||||
(***) =
|
||||
product
|
||||
|
||||
infixr 3 ***
|
||||
|
||||
-- |
|
||||
--
|
||||
-- >>> get (choice fstL sndL) (Left ("abc", 7))
|
||||
-- "abc"
|
||||
--
|
||||
-- >>> get (choice fstL sndL) (Right ("abc", 7))
|
||||
-- 7
|
||||
--
|
||||
-- >>> set (choice fstL sndL) (Left ("abc", 7)) "def"
|
||||
-- Left ("def",7)
|
||||
--
|
||||
-- >>> set (choice fstL sndL) (Right ("abc", 7)) 8
|
||||
-- Right ("abc",8)
|
||||
choice ::
|
||||
Lens s t a b
|
||||
-> Lens q r a b
|
||||
-> Lens (Either s q) (Either t r) a b
|
||||
choice =
|
||||
error "todo: choice"
|
||||
|
||||
-- | An alias for @choice@.
|
||||
(|||) ::
|
||||
Lens s t a b
|
||||
-> Lens q r a b
|
||||
-> Lens (Either s q) (Either t r) a b
|
||||
(|||) =
|
||||
choice
|
||||
|
||||
infixr 2 |||
|
||||
|
||||
----
|
||||
|
||||
type Lens' a b =
|
||||
Lens a a b b
|
||||
|
||||
cityL ::
|
||||
Lens' Locality String
|
||||
cityL p (Locality c t y) =
|
||||
fmap (\c' -> Locality c' t y) (p c)
|
||||
|
||||
stateL ::
|
||||
Lens' Locality String
|
||||
stateL p (Locality c t y) =
|
||||
fmap (\t' -> Locality c t' y) (p t)
|
||||
|
||||
countryL ::
|
||||
Lens' Locality String
|
||||
countryL p (Locality c t y) =
|
||||
fmap (\y' -> Locality c t y') (p y)
|
||||
|
||||
streetL ::
|
||||
Lens' Address String
|
||||
streetL p (Address t s l) =
|
||||
fmap (\t' -> Address t' s l) (p t)
|
||||
|
||||
suburbL ::
|
||||
Lens' Address String
|
||||
suburbL p (Address t s l) =
|
||||
fmap (\s' -> Address t s' l) (p s)
|
||||
|
||||
localityL ::
|
||||
Lens' Address Locality
|
||||
localityL p (Address t s l) =
|
||||
fmap (\l' -> Address t s l') (p l)
|
||||
|
||||
ageL ::
|
||||
Lens' Person Int
|
||||
ageL p (Person a n d) =
|
||||
fmap (\a' -> Person a' n d) (p a)
|
||||
|
||||
nameL ::
|
||||
Lens' Person String
|
||||
nameL p (Person a n d) =
|
||||
fmap (\n' -> Person a n' d) (p n)
|
||||
|
||||
addressL ::
|
||||
Lens' Person Address
|
||||
addressL p (Person a n d) =
|
||||
fmap (\d' -> Person a n d') (p d)
|
||||
|
||||
intAndIntL ::
|
||||
Lens' (IntAnd a) Int
|
||||
intAndIntL p (IntAnd n a) =
|
||||
fmap (\n' -> IntAnd n' a) (p n)
|
||||
|
||||
-- lens for polymorphic update
|
||||
intAndL ::
|
||||
Lens (IntAnd a) (IntAnd b) a b
|
||||
intAndL p (IntAnd n a) =
|
||||
fmap (\a' -> IntAnd n a') (p a)
|
||||
|
||||
-- |
|
||||
--
|
||||
-- >>> get (suburbL |. addressL) fred
|
||||
-- "Fredville"
|
||||
--
|
||||
-- >>> get (suburbL |. addressL) mary
|
||||
-- "Maryland"
|
||||
getSuburb ::
|
||||
Person
|
||||
-> String
|
||||
getSuburb =
|
||||
error "todo: getSuburb"
|
||||
|
||||
-- |
|
||||
--
|
||||
-- >>> setStreet fred "Some Other St"
|
||||
-- Person 24 "Fred" (Address "Some Other St" "Fredville" (Locality "Fredmania" "New South Fred" "Fredalia"))
|
||||
--
|
||||
-- >>> setStreet mary "Some Other St"
|
||||
-- Person 28 "Mary" (Address "Some Other St" "Maryland" (Locality "Mary Mary" "Western Mary" "Maristan"))
|
||||
setStreet ::
|
||||
Person
|
||||
-> String
|
||||
-> Person
|
||||
setStreet =
|
||||
error "todo: setStreet"
|
||||
|
||||
-- |
|
||||
--
|
||||
-- >>> getAgeAndCountry (fred, maryLocality)
|
||||
-- (24,"Maristan")
|
||||
--
|
||||
-- >>> getAgeAndCountry (mary, fredLocality)
|
||||
-- (28,"Fredalia")
|
||||
getAgeAndCountry ::
|
||||
(Person, Locality)
|
||||
-> (Int, String)
|
||||
getAgeAndCountry =
|
||||
error "todo: getAgeAndCountry"
|
||||
|
||||
-- |
|
||||
--
|
||||
-- >>> setCityAndLocality (fred, maryAddress) ("Some Other City", fredLocality)
|
||||
-- (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"))
|
||||
--
|
||||
-- >>> setCityAndLocality (mary, fredAddress) ("Some Other City", maryLocality)
|
||||
-- (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"))
|
||||
setCityAndLocality ::
|
||||
(Person, Address) -> (String, Locality) -> (Person, Address)
|
||||
setCityAndLocality =
|
||||
error "todo: setCityAndLocality"
|
||||
|
||||
-- |
|
||||
--
|
||||
-- >>> getSuburbOrCity (Left maryAddress)
|
||||
-- "Maryland"
|
||||
--
|
||||
-- >>> getSuburbOrCity (Right fredLocality)
|
||||
-- "Fredmania"
|
||||
getSuburbOrCity ::
|
||||
Either Address Locality
|
||||
-> String
|
||||
getSuburbOrCity =
|
||||
error "todo: getSuburbOrCity"
|
||||
|
||||
-- |
|
||||
--
|
||||
-- >>> setStreetOrState (Right maryLocality) "Some Other State"
|
||||
-- Right (Locality "Mary Mary" "Some Other State" "Maristan")
|
||||
--
|
||||
-- >>> setStreetOrState (Left fred) "Some Other St"
|
||||
-- Left (Person 24 "Fred" (Address "Some Other St" "Fredville" (Locality "Fredmania" "New South Fred" "Fredalia")))
|
||||
setStreetOrState ::
|
||||
Either Person Locality
|
||||
-> String
|
||||
-> Either Person Locality
|
||||
setStreetOrState =
|
||||
error "todo: setStreetOrState"
|
||||
|
||||
-- |
|
||||
--
|
||||
-- >>> modifyCityUppercase fred
|
||||
-- Person 24 "Fred" (Address "15 Fred St" "Fredville" (Locality "FREDMANIA" "New South Fred" "Fredalia"))
|
||||
--
|
||||
-- >>> modifyCityUppercase mary
|
||||
-- Person 28 "Mary" (Address "83 Mary Ln" "Maryland" (Locality "MARY MARY" "Western Mary" "Maristan"))
|
||||
modifyCityUppercase ::
|
||||
Person
|
||||
-> Person
|
||||
modifyCityUppercase =
|
||||
error "todo: modifyCityUppercase"
|
||||
|
||||
-- |
|
||||
--
|
||||
-- >>> modifyIntAndLengthEven (IntAnd 10 "abc")
|
||||
-- IntAnd 10 False
|
||||
--
|
||||
-- >>> modifyIntAndLengthEven (IntAnd 10 "abcd")
|
||||
-- IntAnd 10 True
|
||||
modifyIntAndLengthEven ::
|
||||
IntAnd [a]
|
||||
-> IntAnd Bool
|
||||
modifyIntAndLengthEven =
|
||||
error "todo: modifyIntAndLengthEven"
|
||||
|
||||
----
|
||||
|
||||
-- |
|
||||
--
|
||||
-- >>> over traverseLocality (map toUpper) (Locality "abc" "def" "ghi")
|
||||
-- Locality "ABC" "DEF" "GHI"
|
||||
traverseLocality ::
|
||||
Traversal' Locality String
|
||||
traverseLocality =
|
||||
error "todo: traverseLocality"
|
||||
|
||||
-- |
|
||||
--
|
||||
-- >>> over intOrIntP (*10) (IntOrIs 3)
|
||||
-- IntOrIs 30
|
||||
--
|
||||
-- >>> over intOrIntP (*10) (IntOrIsNot "abc")
|
||||
-- IntOrIsNot "abc"
|
||||
intOrIntP ::
|
||||
Prism' (IntOr a) Int
|
||||
intOrIntP =
|
||||
error "todo: intOrIntP"
|
||||
|
||||
intOrP ::
|
||||
Prism (IntOr a) (IntOr b) a b
|
||||
intOrP =
|
||||
error "todo: intOrP"
|
||||
|
||||
-- |
|
||||
--
|
||||
-- >> over intOrP (even . length) (IntOrIsNot "abc")
|
||||
-- IntOrIsNot False
|
||||
--
|
||||
-- >>> over intOrP (even . length) (IntOrIsNot "abcd")
|
||||
-- IntOrIsNot True
|
||||
--
|
||||
-- >>> over intOrP (even . length) (IntOrIs 10)
|
||||
-- IntOrIs 10
|
||||
intOrLengthEven ::
|
||||
IntOr [a]
|
||||
-> IntOr Bool
|
||||
intOrLengthEven =
|
||||
error "todo: intOrLengthEven"
|
||||
|
|
@ -1,4 +1,4 @@
|
|||
module Lets.Lens.Profunctor (
|
||||
module Lets.Profunctor (
|
||||
Profunctor(dimap)
|
||||
) where
|
||||
|
||||
Loading…
Reference in New Issue