Full Code of data61/lets-lens for AI

Repository: data61/lets-lens
Branch: master
Commit: 69555cd462e3
Files: 19
Total size: 59.7 KB

Directory structure:
gitextract_x_dmflpo/

├── .ghci
├── .gitignore
├── LICENCE
├── README.markdown
├── Setup.hs
├── changelog
├── default.nix
├── lets-lens.cabal
├── lets-lens.nix
├── shell.nix
├── src/
│   ├── Lets/
│   │   ├── Choice.hs
│   │   ├── Data.hs
│   │   ├── GetSetLens.hs
│   │   ├── Lens.hs
│   │   ├── OpticPolyLens.hs
│   │   ├── Profunctor.hs
│   │   └── StoreLens.hs
│   └── Lets.hs
└── test/
    └── doctests.hs

================================================
FILE CONTENTS
================================================

================================================
FILE: .ghci
================================================
:set -isrc
:l src/Lets.hs
:set prompt ">> "
:set -Wall
:set -fno-warn-unused-binds
:set -fno-warn-unused-do-bind
:set -fno-warn-unused-imports
:set -fno-warn-type-defaults
:set -XScopedTypeVariables
:set -XOverloadedStrings


================================================
FILE: .gitignore
================================================
*~
*#*

# CABAL
/dist
/dist-newstyle
/cabal-dev
/.cabal-sandbox
/cabal.sandbox.config
.ghc.environment.*

# Haskell Program Coverage
/.hpc

# Leksah
*.lkshs

# Intellij IDEA
/.idea

# darcs
/_darcs

# ctags
TAGS

# sbt
/project
/target

*.swp



================================================
FILE: LICENCE
================================================
Copyright 2012-2015 National ICT Australia Limited

All rights reserved.

Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions
are met:
1. Redistributions of source code must retain the above copyright
   notice, this list of conditions and the following disclaimer.
2. Redistributions in binary form must reproduce the above copyright
   notice, this list of conditions and the following disclaimer in the
   documentation and/or other materials provided with the distribution.
3. Neither the name of the author nor the names of his contributors
   may be used to endorse or promote products derived from this software
   without specific prior written permission.

THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHORS OR CONTRIBUTORS BE LIABLE
FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
SUCH DAMAGE.


================================================
FILE: README.markdown
================================================
# Let's Lens

![System-F](https://logo.systemf.com.au/systemf-450x450.png)

Let's Lens presents a series of exercises, in a similar format to
[the Data61 functional programming course material](http://github.com/data61/fp-course).
The subject of the exercises is around the concept of lenses, initially proposed
by Foster et al., to solve the view-update problem of relational databases.

The theories around lenses have been advanced significantly in recent years,
resulting in a library, implemented in Haskell, called `lens`.

http://hackage.haskell.org/package/lens

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` module.

Exercises can be recognised by filling in a function body that has a placeholder
of `error "todo: <function-name>"`.

----

### Exercise modules

##### `Lets.GetSetLens`

This module presents a series of exercises, representing lenses as a traditional
pair of "`get` and `set`" functions. This representation may be beneficial as it
easily appeals to an intuition of "what a lens is", however, it is outdated. 

These exercises are useful to gain an initial understanding of the problems that
lenses solve, as well as to gain an insight into the history of lenses and how
the theories have developed over time.

##### `Lets.StoreLens`

This series of exercises is similar to `Lets.GetSetLens`, however, using a
slightly altered representation of a lens, based on the `Store` comonad, which
fuses the typical `get` and `set` operations into a data structure. This
representation is described in detail in
*Morris, Tony. "Asymmetric Lenses in Scala." (2012).*

##### `Lets.OpticPolyLens`

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`

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
on to described other structures to solve various practical problems such as
*multi-update* and *partial update*.

This representation presents a generalisation, permitting *polymorphic update*
over structures. After lenses are derived, further concepts are introduced, such
as `Fold`s, `Traversal`s and `Prism`s.

----

### Credits

* Edward Kmett on the [derivation of lenses](https://github.com/ekmett/lens/wiki/Derivation)


================================================
FILE: Setup.hs
================================================
import Distribution.Simple
main = defaultMain


================================================
FILE: changelog
================================================
0.0.1

Init



================================================
FILE: default.nix
================================================
{ nixpkgs ? import <nixpkgs> {}, compiler ? "default" }:
let
  inherit (nixpkgs) pkgs;
  haskellPackages = if compiler == "default"
                       then pkgs.haskellPackages
                       else pkgs.haskell.packages.${compiler};

  tasty-hedgehog-github = pkgs.callPackage (pkgs.fetchFromGitHub {
    owner = "qfpl";
    repo = "tasty-hedgehog";
    rev = "5da389f5534943b430300a213c5ffb5d0e13459e";
    sha256 = "04pmr9q70gakd327sywpxr7qp8jnl3b0y2sqxxxcj6zj2q45q38m";
  }) {};

  modifiedHaskellPackages = haskellPackages.override {
    overrides = self: super: {
      tasty-hedgehog =
        if super ? tasty-hedgehog
        then super.tasty-hedgehog
        else tasty-hedgehog-github;
    };
  };

  lets-lens = modifiedHaskellPackages.callPackage ./lets-lens.nix {};
in
  lets-lens


================================================
FILE: lets-lens.cabal
================================================
name:                 lets-lens
version:              0.0.1
license:              BSD3
license-file:         LICENCE
author:               Tony Morris <ʇǝu˙sıɹɹoɯʇ@ןןǝʞsɐɥ>
maintainer:           Tony Morris <ʇǝu˙sıɹɹoɯʇ@ןןǝʞsɐɥ>
copyright:            Copyright (C) 2015-2016 National ICT Australia Limited,
                      Copyright (c) 2017-2018, Commonwealth Scientific and Industrial Research Organisation (CSIRO) ABN 41 687 119 230.
synopsis:             Source code for exercises on the lens concept
category:             Education
description:          Source code for exercises on the lens concept
homepage:             https://github.com/data61/lets-lens
bug-reports:          https://github.com/data61/lets-lens/issues
cabal-version:        >= 1.10
build-type:           Simple
extra-source-files:   changelog

source-repository     head
  type:               git
  location:           git@github.com:data61/lets-lens.git

flag                  small_base
  description:        Choose the new, split-up base package.

library
  default-language:   Haskell2010

  build-depends:      base >= 4.8 && < 5
                      , containers >= 0.4.0.0

  ghc-options:        -Wall
                      -fno-warn-unused-binds
                      -fno-warn-unused-do-bind
                      -fno-warn-unused-imports
                      -fno-warn-type-defaults

  hs-source-dirs:     src

  exposed-modules:    Lets
                      Lets.Choice
                      Lets.Data
                      Lets.GetSetLens
                      Lets.Lens
                      Lets.OpticPolyLens
                      Lets.Profunctor
                      Lets.StoreLens

test-suite            doctests
  type:
                      exitcode-stdio-1.0

  main-is:
                      doctests.hs

  default-language:
                      Haskell2010

  build-depends:
                      base < 5 && >= 3
                      , doctest >= 0.9.7
                      , filepath >= 1.3
                      , directory >= 1.1
                      , QuickCheck >= 2.0
                      , template-haskell >= 2.8

  ghc-options:
                      -Wall
                      -threaded

  hs-source-dirs:
                      test


================================================
FILE: lets-lens.nix
================================================
{ mkDerivation, base, containers, directory, doctest, filepath
, QuickCheck, stdenv, template-haskell
}:
mkDerivation {
  pname = "lets-lens";
  version = "0.0.1";
  src = ./.;
  libraryHaskellDepends = [ base containers ];
  testHaskellDepends = [
    base directory doctest filepath QuickCheck template-haskell
  ];
  homepage = "https://github.com/data61/lets-lens";
  description = "Source code for exercises on the lens concept";
  license = stdenv.lib.licenses.bsd3;
}


================================================
FILE: shell.nix
================================================
{ nixpkgs ? import <nixpkgs> {}, compiler ? "default" }:
let
  inherit (nixpkgs) pkgs;
  drv = import ./default.nix { inherit nixpkgs compiler; };
  drvWithTools = pkgs.haskell.lib.addBuildDepends drv [ pkgs.cabal-install ];
in
  if pkgs.lib.inNixShell then drvWithTools.env else drvWithTools


================================================
FILE: src/Lets/Choice.hs
================================================
module Lets.Choice (
  Choice(..)
) where

import Lets.Data
import Lets.Profunctor

diswap ::
  Profunctor p =>
  p (Either a b) (Either c d)
  -> p (Either b a) (Either d c)
diswap =
  let swap = either Right Left 
  in dimap swap swap

-- | Map on left or right of @Either@. Only one of @left@ or @right@ needs to be
-- provided.
class Profunctor p => Choice p where
  left ::
    p a b
    -> p (Either a c) (Either b c)
  left =
    diswap . right

  right ::
    p a b
    -> p (Either c a) (Either c b)
  right =
    diswap . left

instance Choice (->) where
  left f =
    either (Left . f) Right
  right f =
    either Left (Right . f)

instance Choice Tagged where
  left (Tagged x) =
    Tagged (Left x)
  right (Tagged x) =
    Tagged (Right x)



================================================
FILE: src/Lets/Data.hs
================================================
module Lets.Data (
  Locality(..)
, Address(..)
, Person(..)
, IntAnd(..)
, IntOr(..)
, fredLocality
, fredAddress
, fred
, maryLocality
, maryAddress
, mary
, Store(..)
, Const (..)
, Tagged(..)
, Identity(..)
, AlongsideLeft(..)
, AlongsideRight(..)
) where

import Control.Applicative(Applicative(..))
import Data.Monoid(Monoid(..))

data Locality =
  Locality
    String -- city
    String -- state
    String -- country
  deriving (Eq, Show)  

data Address =
  Address
    String -- street
    String -- suburb
    Locality
  deriving (Eq, Show)  

data Person =
  Person
    Int -- age
    String -- name
    Address -- address
  deriving (Eq, Show)

data IntAnd a =
  IntAnd
    Int
    a
  deriving (Eq, Show)

data IntOr a =
  IntOrIs Int
  | IntOrIsNot a
  deriving (Eq, Show)

fredLocality ::
  Locality
fredLocality =
  Locality
    "Fredmania"
    "New South Fred"
    "Fredalia"

fredAddress ::
  Address
fredAddress =
  Address
    "15 Fred St"
    "Fredville"
    fredLocality

fred ::
  Person
fred =
  Person
    24
    "Fred"
    fredAddress

maryLocality ::
  Locality
maryLocality =
  Locality
    "Mary Mary"
    "Western Mary"
    "Maristan"

maryAddress ::
  Address
maryAddress =
  Address
    "83 Mary Ln"
    "Maryland"
    maryLocality

mary ::
  Person
mary =
  Person
    28
    "Mary"
    maryAddress

----

data Store s a =
  Store
    (s -> a)
    s

data Const a b =
  Const {
    getConst :: 
      a
  }
  deriving (Eq, Show)

instance Functor (Const a) where
  fmap _ (Const a) =
    Const a

instance Monoid a => Applicative (Const a) where
  pure _ =
    Const mempty
  Const f <*> Const a =
    Const (f `mappend` a)

data Tagged a b = 
  Tagged {
    getTagged ::
      b
  }
  deriving (Eq, Show)

instance Functor (Tagged a) where
  fmap f (Tagged b) =
    Tagged (f b)

instance Applicative (Tagged a) where
  pure =
    Tagged
  Tagged f <*> Tagged a =
    Tagged (f a)

data Identity a =
  Identity {
    getIdentity ::
      a
  }
  deriving (Eq, Show)

instance Functor Identity where
  fmap f (Identity a) =
    Identity (f a)

instance Applicative Identity where
  pure =
    Identity
  Identity f <*> Identity a =
    Identity (f a)

data AlongsideLeft f b a =
  AlongsideLeft {
    getAlongsideLeft :: 
      f (a, b)
  }

instance Functor f => Functor (AlongsideLeft f b) where
  fmap f (AlongsideLeft x) =
    AlongsideLeft (fmap (\(a, b) -> (f a, b)) x)

data AlongsideRight f a b =
  AlongsideRight {
    getAlongsideRight ::
      f (a, b)
  }

instance Functor f => Functor (AlongsideRight f a) where
  fmap f (AlongsideRight x) =
    AlongsideRight (fmap (\(a, b) -> (a, f b)) x)


================================================
FILE: src/Lets/GetSetLens.hs
================================================
module Lets.GetSetLens (
  Lens(..)
, getsetLaw
, setgetLaw
, setsetLaw
, get
, set
, modify
, (%~)
, (.~)
, fmodify
, (|=)
, fstL
, sndL
, mapL
, setL
, compose
, (|.)
, identity
, product
, (***)
, choice
, (|||)
, cityL
, countryL
, streetL
, suburbL
, localityL
, ageL
, nameL
, addressL
, getSuburb
, setStreet
, getAgeAndCountry
, setCityAndLocality
, getSuburbOrCity
, setStreetOrState
, modifyCityUppercase
) where

import Control.Applicative(Applicative((<*>)))
import Data.Char(toUpper)
import Data.Map(Map)
import qualified Data.Map as Map(insert, delete, lookup)
import Data.Set(Set)
import qualified Data.Set as Set(insert, delete, member)
import Lets.Data(Person(Person), Locality(Locality), Address(Address))
import Prelude hiding (product)

-- $setup
-- >>> import qualified Data.Map as Map(fromList)
-- >>> import qualified Data.Set as Set(fromList)
-- >>> import Data.Bool(bool)
-- >>> import Data.Char(ord)
-- >>> import Lets.Data

data Lens a b =
  Lens
    (a -> b -> a)
    (a -> b)

-- |
--
-- >>> get fstL (0 :: Int, "abc")
-- 0
--
-- >>> get sndL ("abc", 0 :: Int)
-- 0
--
-- prop> let types = (x :: Int, y :: String) in get fstL (x, y) == x
--
-- prop> let types = (x :: Int, y :: String) in get sndL (x, y) == y
get ::
  Lens a b
  -> a
  -> b
get (Lens _ g) =
  g

-- |
--
-- >>> set fstL (0 :: Int, "abc") 1
-- (1,"abc")
--
-- >>> set sndL ("abc", 0 :: Int) 1
-- ("abc",1)
--
-- prop> let types = (x :: Int, y :: String) in set fstL (x, y) z == (z, y)
--
-- prop> let types = (x :: Int, y :: String) in set sndL (x, y) z == (x, z)
set ::
  Lens a b
  -> a 
  -> b
  -> a
set (Lens s _) a =
  s a

-- | The get/set law of lenses. This function should always return @True@.
getsetLaw ::
  Eq a =>
  Lens a b
  -> a
  -> Bool
getsetLaw l =
  \a -> set l a (get l a) == a
  
-- | The set/get law of lenses. This function should always return @True@.
setgetLaw ::
  Eq b =>
  Lens a b
  -> a
  -> b
  -> Bool
setgetLaw l a b =
  get l (set l a b) == b
  
-- | The set/set law of lenses. This function should always return @True@.
setsetLaw ::
  Eq a =>
  Lens a b
  -> a
  -> b
  -> b
  -> Bool
setsetLaw l a b1 b2 =
  set l (set l a b1) b2 == set l a b2

----

-- |
--
-- >>> 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 a b
  -> (b -> b)
  -> a
  -> a
modify =
  error "todo: modify"

-- | An alias for @modify@.
(%~) ::
  Lens a b
  -> (b -> b)
  -> a
  -> a
(%~) =
  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 a b
  -> b
  -> a
  -> a
(.~) =
  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 a b
  -> (b -> f b)
  -> a
  -> f a
fmodify =
  error "todo: fmodify"

-- |
--
-- >>> fstL |= Just 3 $ (7, "abc")
-- Just (3,"abc")
--
-- >>> (fstL |= (+1) $ (3, "abc")) 17
-- (18,"abc")
(|=) ::
  Functor f =>
  Lens a b
  -> f b
  -> a
  -> f a
(|=) =
  error "todo: (|=)"

infixl 5 |=

-- |
--
-- >>> modify fstL (*10) (3, "abc")
-- (30,"abc")
--
-- prop> let types = (x :: Int, y :: String) in getsetLaw fstL (x, y)
--
-- prop> let types = (x :: Int, y :: String) in setgetLaw fstL (x, y) z
--
-- prop> let types = (x :: Int, y :: String) in setsetLaw fstL (x, y) z
fstL ::
  Lens (x, y) x
fstL =
  error "todo: fstL"

-- |
--
-- >>> modify sndL (++ "def") (13, "abc")
-- (13,"abcdef")
--
-- prop> let types = (x :: Int, y :: String) in getsetLaw sndL (x, y)
--
-- prop> let types = (x :: Int, y :: String) in setgetLaw sndL (x, y) z
--
-- prop> let types = (x :: Int, y :: String) in setsetLaw sndL (x, y) z
sndL ::
  Lens (x, y) y
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) (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 k) 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 b c
  -> Lens a b
  -> Lens a c
compose =
  error "todo: compose"

-- | An alias for @compose@.
(|.) ::
  Lens b c
  -> Lens a b
  -> Lens a c
(|.) =
  compose

infixr 9 |.

-- |
--
-- >>> get identity 3
-- 3
--
-- >>> set identity 3 4
-- 4
identity ::
  Lens a a
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 a b
  -> Lens c d
  -> Lens (a, c) (b, d)
product =
  error "todo: product"

-- | An alias for @product@.
(***) ::
  Lens a b
  -> Lens c d
  -> Lens (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 a x
  -> Lens b x
  -> Lens (Either a b) x
choice =
  error "todo: choice"

-- | An alias for @choice@.
(|||) ::
  Lens a x
  -> Lens b x
  -> Lens (Either a b) x
(|||) =
  choice

infixr 2 |||

----

cityL ::
  Lens Locality String
cityL =
  Lens
    (\(Locality _ t y) c -> Locality c t y)
    (\(Locality c _ _) -> c)

stateL ::
  Lens Locality String
stateL =
  Lens
    (\(Locality c _ y) t -> Locality c t y)
    (\(Locality _ t _) -> t)

countryL ::
  Lens Locality String
countryL =
  Lens
    (\(Locality c t _) y -> Locality c t y)
    (\(Locality _ _ y) -> y)

streetL ::
  Lens Address String
streetL =
  Lens
    (\(Address _ s l) t -> Address t s l)
    (\(Address t _ _) -> t)

suburbL ::
  Lens Address String
suburbL =
  Lens
    (\(Address t _ l) s -> Address t s l)
    (\(Address _ s _) -> s)

localityL ::
  Lens Address Locality
localityL =
  Lens
    (\(Address t s _) l -> Address t s l)
    (\(Address _ _ l) -> l)

ageL ::
  Lens Person Int
ageL =
  Lens
    (\(Person _ n d) a -> Person a n d)
    (\(Person a _ _) -> a)

nameL ::
  Lens Person String
nameL =
  Lens
    (\(Person a _ d) n -> Person a n d)
    (\(Person _ n _) -> n)

addressL ::
  Lens Person Address
addressL =
  Lens
    (\(Person a n _) d -> Person a n d)
    (\(Person _ _ d) -> d)

-- |
--
-- >>> getSuburb fred
-- "Fredville"
--
-- >>> getSuburb 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"


================================================
FILE: src/Lets/Lens.hs
================================================
{-# LANGUAGE RankNTypes #-}

module Lets.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.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.Bool(bool)
-- >>> import Data.Char(ord)
-- >>> import Lets.Data

-- 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 @foldMap@ can be recovered from @traverse@ using @Const@.
--
-- /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"

-- |
--
-- To work on `Map k a`:
--   Map.lookup :: Ord k => k -> Map k a -> Maybe a
--   Map.insert :: Ord k => k -> a -> Map k a -> Map k a
--   Map.delete :: Ord k => k -> Map k a -> Map k a
--
-- >>> 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"

-- |
--
-- To work on `Set a`:
--   Set.insert :: Ord a => a -> Set a -> Set a
--   Set.member :: Ord a => a -> Set a -> Bool
--   Set.delete :: Ord a => a -> Set a -> Set a
--
-- >>> 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)

-- |
--
-- >>> getSuburb fred
-- "Fredville"
--
-- >>> getSuburb 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"

-- |
--
-- >> intOrLengthEven (IntOrIsNot "abc")
-- IntOrIsNot False
--
-- >>> intOrLengthEven (IntOrIsNot "abcd")
-- IntOrIsNot True
--
-- >>> intOrLengthEven (IntOrIs 10)
-- IntOrIs 10
intOrLengthEven ::
  IntOr [a]
  -> IntOr Bool
intOrLengthEven =
  error "todo: intOrLengthEven"


================================================
FILE: src/Lets/OpticPolyLens.hs
================================================
{-# LANGUAGE RankNTypes #-}

module Lets.OpticPolyLens (
  Lens(..)
, getsetLaw
, setgetLaw
, setsetLaw
, get
, set
, modify
, (%~)
, (.~)
, fmodify
, (|=)
, fstL
, sndL
, mapL
, setL
, compose
, (|.)
, identity
, product
, (***)
, choice
, (|||)
, cityL
, countryL
, streetL
, suburbL
, localityL
, ageL
, nameL
, addressL
, intAndIntL
, intAndL
, getSuburb
, setStreet
, getAgeAndCountry
, setCityAndLocality
, getSuburbOrCity
, setStreetOrState
, modifyCityUppercase
, modifyIntandLengthEven
) where

import Data.Char(toUpper)
import Data.Map(Map)
import qualified Data.Map as Map(insert, delete, lookup)
import Data.Set(Set)
import qualified Data.Set as Set(insert, delete, member)
import Lets.Data(AlongsideLeft(AlongsideLeft, getAlongsideLeft), AlongsideRight(AlongsideRight, getAlongsideRight), Identity(Identity, getIdentity), Const(Const, getConst), IntAnd(IntAnd), Person(Person), Locality(Locality), Address(Address))
import Prelude hiding (product)

-- $setup
-- >>> import qualified Data.Map as Map(fromList)
-- >>> import qualified Data.Set as Set(fromList)
-- >>> import Data.Bool(bool)
-- >>> import Data.Char(ord)
-- >>> import Lets.Data

data Lens s t a b =
  Lens
    (forall f. Functor f => (a -> f b) -> s -> f t)

get ::
  Lens s t a b
  -> s
  -> a
get (Lens r) =
  getConst . r Const

set ::
  Lens s t a b
  -> s
  -> b
  -> t
set (Lens r) a b =
  getIdentity (r (const (Identity b)) a)

-- | The get/set law of lenses. This function should always return @True@.
getsetLaw ::
  Eq s =>
  Lens s s a a
  -> s
  -> Bool
getsetLaw l =
  \a -> set l a (get l a) == a

-- | The set/get law of lenses. This function should always return @True@.
setgetLaw ::
  Eq a =>
  Lens s s a a
  -> s
  -> a
  -> Bool
setgetLaw l a b =
  get l (set l a b) == b

-- | The set/set law of lenses. This function should always return @True@.
setsetLaw ::
  Eq s =>
  Lens s s a b
  -> s
  -> b
  -> b
  -> Bool 
setsetLaw l a b1 b2 =
  set l (set l a b1) b2 == set l a b2

----

-- |
--
-- >>> 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")
--
-- prop> let types = (x :: Int, y :: String) in getsetLaw fstL (x, y)
--
-- prop> let types = (x :: Int, y :: String) in setgetLaw fstL (x, y) z
--
-- prop> let types = (x :: Int, y :: String) in setsetLaw fstL (x, y) z
fstL ::
  Lens (a, x) (b, x) a b
fstL =
  error "todo: fstL"

-- |
--
-- >>> modify sndL (++ "def") (13, "abc")
-- (13,"abcdef")
--
-- prop> let types = (x :: Int, y :: String) in getsetLaw sndL (x, y)
--
-- prop> let types = (x :: Int, y :: String) in setgetLaw sndL (x, y) z
--
-- prop> let types = (x :: Int, y :: String) in setsetLaw sndL (x, y) z
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 k) (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 =
  Lens
    (\p (Locality c t y) -> fmap (\c' -> Locality c' t y) (p c))

stateL ::
  Lens' Locality String
stateL =
  Lens
    (\p (Locality c t y) -> fmap (\t' -> Locality c t' y) (p t))

countryL ::
  Lens' Locality String
countryL =
  Lens
    (\p (Locality c t y) -> fmap (\y' -> Locality c t y') (p y))

streetL ::
  Lens' Address String
streetL =
  Lens
    (\p (Address t s l) -> fmap (\t' -> Address t' s l) (p t))

suburbL ::
  Lens' Address String
suburbL =
  Lens
    (\p (Address t s l) -> fmap (\s' -> Address t s' l) (p s))

localityL ::
  Lens' Address Locality
localityL =
  Lens
    (\p (Address t s l) -> fmap (\l' -> Address t s l') (p l))

ageL ::
  Lens' Person Int
ageL =
  Lens
    (\p (Person a n d) -> fmap (\a' -> Person a' n d) (p a))

nameL ::
  Lens' Person String
nameL =
  Lens
    (\p (Person a n d) -> fmap (\n' -> Person a n' d) (p n))

addressL ::
  Lens' Person Address
addressL =
  Lens
    (\p (Person a n d) -> fmap (\d' -> Person a n d') (p d))

intAndIntL ::
  Lens' (IntAnd a) Int
intAndIntL =
  Lens
    (\p (IntAnd n a) -> fmap (\n' -> IntAnd n' a) (p n))

-- lens for polymorphic update
intAndL ::
  Lens (IntAnd a) (IntAnd b) a b
intAndL =
  Lens
    (\p (IntAnd n a) -> fmap (\a' -> IntAnd n a') (p a))

-- |
--
-- >>> getSuburb fred
-- "Fredville"
--
-- >>> getSuburb 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 =
  get (suburbL ||| cityL)

-- |
--
-- >>> 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 =
  set (streetL |. addressL ||| stateL)

-- |
--
-- >>> 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 =
  cityL |. localityL |. addressL %~ map toUpper

-- |
--
-- >>> modify intAndL (even . length) (IntAnd 10 "abc")
-- IntAnd 10 False
--
-- >>> modify intAndL (even . length) (IntAnd 10 "abcd")
-- IntAnd 10 True
modifyIntandLengthEven ::
  IntAnd [a]
  -> IntAnd Bool
modifyIntandLengthEven =
  intAndL %~ even . length


================================================
FILE: src/Lets/Profunctor.hs
================================================
module Lets.Profunctor (
  Profunctor(dimap)
) where

import Lets.Data

-- | A profunctor is a binary functor, with the first argument in contravariant
-- (negative) position and the second argument in covariant (positive) position.
class Profunctor p where
  dimap ::
    (b -> a)
    -> (c -> d)
    -> p a c
    -> p b d

instance Profunctor (->) where
  dimap f g = \h -> g . h . f

instance Profunctor Tagged where
  dimap _ g (Tagged x) =
    Tagged (g x)


================================================
FILE: src/Lets/StoreLens.hs
================================================
module Lets.StoreLens (
  Store(..)
, setS
, getS
, mapS
, duplicateS
, extendS
, extractS
, Lens(..)
, getsetLaw
, setgetLaw
, setsetLaw
, get
, set
, modify
, (%~)
, (.~)
, fmodify
, (|=)
, fstL
, sndL
, mapL
, setL
, compose
, (|.)
, identity
, product
, (***)
, choice
, (|||)
, cityL
, stateL
, countryL
, streetL
, suburbL
, localityL
, ageL
, nameL
, addressL
, getSuburb
, setStreet
, getAgeAndCountry
, setCityAndLocality
, getSuburbOrCity
, setStreetOrState
, modifyCityUppercase
) where

import Control.Applicative(Applicative((<*>)))
import Data.Char(toUpper)
import Data.Functor((<$>))
import Data.Map(Map)
import qualified Data.Map as Map(insert, delete, lookup)
import Data.Set(Set)
import qualified Data.Set as Set(insert, delete, member)
import Lets.Data(Store(Store), Person(Person), Locality(Locality), Address(Address))
import Prelude hiding (product)

-- $setup
-- >>> import qualified Data.Map as Map(fromList)
-- >>> import qualified Data.Set as Set(fromList)
-- >>> import Data.Bool(bool)
-- >>> import Data.Char(ord)
-- >>> import Lets.Data

setS ::
  Store s a
  -> s
  -> a
setS (Store s _) =
  s

getS ::
  Store s a
  -> s
getS (Store _ g) =
  g

mapS ::
  (a -> b)
  -> Store s a
  -> Store s b
mapS =
  error "todo: mapS"

duplicateS ::
  Store s a
  -> Store s (Store s a)
duplicateS =
  error "todo: duplicateS"

extendS ::
  (Store s a -> b)
  -> Store s a
  -> Store s b
extendS =
  error "todo: extendS"

extractS ::
  Store s a
  -> a
extractS =
  error "todo: extractS"

----

data Lens a b =
  Lens
    (a -> Store b a)

-- |
--
-- >>> get fstL (0 :: Int, "abc")
-- 0
--
-- >>> get sndL ("abc", 0 :: Int)
-- 0
--
-- prop> let types = (x :: Int, y :: String) in get fstL (x, y) == x
--
-- prop> let types = (x :: Int, y :: String) in get sndL (x, y) == y
get ::
  Lens a b
  -> a
  -> b
get (Lens r) =
  getS . r

-- |
--
-- >>> set fstL (0 :: Int, "abc") 1
-- (1,"abc")
--
-- >>> set sndL ("abc", 0 :: Int) 1
-- ("abc",1)
--
-- prop> let types = (x :: Int, y :: String) in set fstL (x, y) z == (z, y)
--
-- prop> let types = (x :: Int, y :: String) in set sndL (x, y) z == (x, z)
set ::
  Lens a b
  -> a 
  -> b
  -> a
set (Lens r) =
  setS . r

-- | The get/set law of lenses. This function should always return @True@.
getsetLaw ::
  Eq a =>
  Lens a b
  -> a
  -> Bool
getsetLaw l =
  \a -> set l a (get l a) == a
  
-- | The set/get law of lenses. This function should always return @True@.
setgetLaw ::
  Eq b =>
  Lens a b
  -> a
  -> b
  -> Bool
setgetLaw l a b =
  get l (set l a b) == b

-- | The set/set law of lenses. This function should always return @True@.
setsetLaw ::
  Eq a =>
  Lens a b
  -> a
  -> b
  -> b
  -> Bool
setsetLaw l a b1 b2 =
  set l (set l a b1) b2 == set l a b2

----

-- |
--
-- >>> 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 a b
  -> (b -> b)
  -> a
  -> a
modify =
  error "todo: modify"

-- | An alias for @modify@.
(%~) ::
  Lens a b
  -> (b -> b)
  -> a
  -> a
(%~) =
  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 a b
  -> b
  -> a
  -> a
(.~) =
  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 a b
  -> (b -> f b)
  -> a
  -> f a
fmodify =
  error "todo: fmodify"
  
-- |
--
-- >>> fstL |= Just 3 $ (7, "abc")
-- Just (3,"abc")
--
-- >>> (fstL |= (+1) $ (3, "abc")) 17
-- (18,"abc")
(|=) ::
  Functor f =>
  Lens a b
  -> f b
  -> a
  -> f a
(|=) =
  error "todo: (|=)"

infixl 5 |=

-- |
--
-- >>> modify fstL (*10) (3, "abc")
-- (30,"abc")
--
-- prop> let types = (x :: Int, y :: String) in getsetLaw fstL (x, y)
--
-- prop> let types = (x :: Int, y :: String) in setgetLaw fstL (x, y) z
--
-- prop> let types = (x :: Int, y :: String) in setsetLaw fstL (x, y) z
fstL ::
  Lens (x, y) x
fstL =
  error "todo: fstL"

-- |
--
-- >>> modify sndL (++ "def") (13, "abc")
-- (13,"abcdef")
--
-- prop> let types = (x :: Int, y :: String) in getsetLaw sndL (x, y)
--
-- prop> let types = (x :: Int, y :: String) in setgetLaw sndL (x, y) z
--
-- prop> let types = (x :: Int, y :: String) in setsetLaw sndL (x, y) z
sndL ::
  Lens (x, y) y
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) (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 k) 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 b c
  -> Lens a b
  -> Lens a c
compose =
  error "todo: compose"

-- | An alias for @compose@.
(|.) ::
  Lens b c
  -> Lens a b
  -> Lens a c
(|.) =
  compose

infixr 9 |.

-- |
--
-- >>> get identity 3
-- 3
--
-- >>> set identity 3 4
-- 4
identity ::
  Lens a a
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 a b
  -> Lens c d
  -> Lens (a, c) (b, d)
product =
  error "todo: product"

-- | An alias for @product@.
(***) ::
  Lens a b
  -> Lens c d
  -> Lens (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 a x
  -> Lens b x
  -> Lens (Either a b) x
choice =
  error "todo: choice"

-- | An alias for @choice@.
(|||) ::
  Lens a x
  -> Lens b x
  -> Lens (Either a b) x
(|||) =
  choice

infixr 2 |||

----

cityL ::
  Lens Locality String
cityL =
  Lens
    (\(Locality c t y) ->
      Store (\c' -> Locality c' t y) c)

stateL ::
  Lens Locality String
stateL =
  Lens
    (\(Locality c t y) ->
      Store (\t' -> Locality c t' y) t)

countryL ::
  Lens Locality String
countryL =
  Lens
    (\(Locality c t y) ->
      Store (\y' -> Locality c t y') y)

streetL ::
  Lens Address String
streetL =
  Lens
    (\(Address t s l) ->
      Store (\t' -> Address t' s l) t)

suburbL ::
  Lens Address String
suburbL =
  Lens
    (\(Address t s l) ->
      Store (\s' -> Address t s' l) s)

localityL ::
  Lens Address Locality
localityL =
  Lens
    (\(Address t s l) ->
      Store (\l' -> Address t s l') l)

ageL ::
  Lens Person Int
ageL =
  Lens
    (\(Person a n d) ->
      Store (\a' -> Person a' n d) a)

nameL ::
  Lens Person String
nameL =
  Lens
    (\(Person a n d) ->
      Store (\n' -> Person a n' d) n)

addressL ::
  Lens Person Address
addressL =
  Lens
    (\(Person a n d) ->
    Store (\d' -> Person a n d') d)

-- |
--
-- >>> getSuburb fred
-- "Fredville"
--
-- >>> getSuburb 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"


================================================
FILE: src/Lets.hs
================================================
module Lets (
  module L
) where

import Lets.Data as L
import Lets.GetSetLens as L()
import Lets.Lens as L()
import Lets.OpticPolyLens as L()
import Lets.StoreLens as L()


================================================
FILE: test/doctests.hs
================================================
import Test.DocTest

main :: IO ()
main = doctest
  [ "-isrc"
  , "src/Lets/GetSetLens.hs"
  , "src/Lets/Lens.hs"
  , "src/Lets/OpticPolyLens.hs"
  , "src/Lets/StoreLens.hs"
  ]