diff --git a/CHANGELOG.md b/CHANGELOG.md new file mode 100644 --- /dev/null +++ b/CHANGELOG.md @@ -0,0 +1,11 @@ +# Changelog + +`prolens` uses [PVP Versioning][1]. +The changelog is available [on GitHub][2]. + +## 0.0.0.0 + +* Initially created. + +[1]: https://pvp.haskell.org +[2]: https://github.com/kowainik/prolens/releases diff --git a/LICENSE b/LICENSE new file mode 100644 --- /dev/null +++ b/LICENSE @@ -0,0 +1,373 @@ +Mozilla Public License Version 2.0 +================================== + +1. Definitions +-------------- + +1.1. "Contributor" + means each individual or legal entity that creates, contributes to + the creation of, or owns Covered Software. + +1.2. "Contributor Version" + means the combination of the Contributions of others (if any) used + by a Contributor and that particular Contributor's Contribution. + +1.3. "Contribution" + means Covered Software of a particular Contributor. + +1.4. "Covered Software" + means Source Code Form to which the initial Contributor has attached + the notice in Exhibit A, the Executable Form of such Source Code + Form, and Modifications of such Source Code Form, in each case + including portions thereof. + +1.5. "Incompatible With Secondary Licenses" + means + + (a) that the initial Contributor has attached the notice described + in Exhibit B to the Covered Software; or + + (b) that the Covered Software was made available under the terms of + version 1.1 or earlier of the License, but not also under the + terms of a Secondary License. + +1.6. "Executable Form" + means any form of the work other than Source Code Form. + +1.7. "Larger Work" + means a work that combines Covered Software with other material, in + a separate file or files, that is not Covered Software. + +1.8. "License" + means this document. + +1.9. "Licensable" + means having the right to grant, to the maximum extent possible, + whether at the time of the initial grant or subsequently, any and + all of the rights conveyed by this License. + +1.10. "Modifications" + means any of the following: + + (a) any file in Source Code Form that results from an addition to, + deletion from, or modification of the contents of Covered + Software; or + + (b) any new file in Source Code Form that contains any Covered + Software. + +1.11. "Patent Claims" of a Contributor + means any patent claim(s), including without limitation, method, + process, and apparatus claims, in any patent Licensable by such + Contributor that would be infringed, but for the grant of the + License, by the making, using, selling, offering for sale, having + made, import, or transfer of either its Contributions or its + Contributor Version. + +1.12. "Secondary License" + means either the GNU General Public License, Version 2.0, the GNU + Lesser General Public License, Version 2.1, the GNU Affero General + Public License, Version 3.0, or any later versions of those + licenses. + +1.13. "Source Code Form" + means the form of the work preferred for making modifications. + +1.14. "You" (or "Your") + means an individual or a legal entity exercising rights under this + License. For legal entities, "You" includes any entity that + controls, is controlled by, or is under common control with You. For + purposes of this definition, "control" means (a) the power, direct + or indirect, to cause the direction or management of such entity, + whether by contract or otherwise, or (b) ownership of more than + fifty percent (50%) of the outstanding shares or beneficial + ownership of such entity. + +2. License Grants and Conditions +-------------------------------- + +2.1. Grants + +Each Contributor hereby grants You a world-wide, royalty-free, +non-exclusive license: + +(a) under intellectual property rights (other than patent or trademark) + Licensable by such Contributor to use, reproduce, make available, + modify, display, perform, distribute, and otherwise exploit its + Contributions, either on an unmodified basis, with Modifications, or + as part of a Larger Work; and + +(b) under Patent Claims of such Contributor to make, use, sell, offer + for sale, have made, import, and otherwise transfer either its + Contributions or its Contributor Version. + +2.2. Effective Date + +The licenses granted in Section 2.1 with respect to any Contribution +become effective for each Contribution on the date the Contributor first +distributes such Contribution. + +2.3. Limitations on Grant Scope + +The licenses granted in this Section 2 are the only rights granted under +this License. No additional rights or licenses will be implied from the +distribution or licensing of Covered Software under this License. +Notwithstanding Section 2.1(b) above, no patent license is granted by a +Contributor: + +(a) for any code that a Contributor has removed from Covered Software; + or + +(b) for infringements caused by: (i) Your and any other third party's + modifications of Covered Software, or (ii) the combination of its + Contributions with other software (except as part of its Contributor + Version); or + +(c) under Patent Claims infringed by Covered Software in the absence of + its Contributions. + +This License does not grant any rights in the trademarks, service marks, +or logos of any Contributor (except as may be necessary to comply with +the notice requirements in Section 3.4). + +2.4. Subsequent Licenses + +No Contributor makes additional grants as a result of Your choice to +distribute the Covered Software under a subsequent version of this +License (see Section 10.2) or under the terms of a Secondary License (if +permitted under the terms of Section 3.3). + +2.5. Representation + +Each Contributor represents that the Contributor believes its +Contributions are its original creation(s) or it has sufficient rights +to grant the rights to its Contributions conveyed by this License. + +2.6. Fair Use + +This License is not intended to limit any rights You have under +applicable copyright doctrines of fair use, fair dealing, or other +equivalents. + +2.7. Conditions + +Sections 3.1, 3.2, 3.3, and 3.4 are conditions of the licenses granted +in Section 2.1. + +3. Responsibilities +------------------- + +3.1. Distribution of Source Form + +All distribution of Covered Software in Source Code Form, including any +Modifications that You create or to which You contribute, must be under +the terms of this License. You must inform recipients that the Source +Code Form of the Covered Software is governed by the terms of this +License, and how they can obtain a copy of this License. You may not +attempt to alter or restrict the recipients' rights in the Source Code +Form. + +3.2. Distribution of Executable Form + +If You distribute Covered Software in Executable Form then: + +(a) such Covered Software must also be made available in Source Code + Form, as described in Section 3.1, and You must inform recipients of + the Executable Form how they can obtain a copy of such Source Code + Form by reasonable means in a timely manner, at a charge no more + than the cost of distribution to the recipient; and + +(b) You may distribute such Executable Form under the terms of this + License, or sublicense it under different terms, provided that the + license for the Executable Form does not attempt to limit or alter + the recipients' rights in the Source Code Form under this License. + +3.3. Distribution of a Larger Work + +You may create and distribute a Larger Work under terms of Your choice, +provided that You also comply with the requirements of this License for +the Covered Software. If the Larger Work is a combination of Covered +Software with a work governed by one or more Secondary Licenses, and the +Covered Software is not Incompatible With Secondary Licenses, this +License permits You to additionally distribute such Covered Software +under the terms of such Secondary License(s), so that the recipient of +the Larger Work may, at their option, further distribute the Covered +Software under the terms of either this License or such Secondary +License(s). + +3.4. Notices + +You may not remove or alter the substance of any license notices +(including copyright notices, patent notices, disclaimers of warranty, +or limitations of liability) contained within the Source Code Form of +the Covered Software, except that You may alter any license notices to +the extent required to remedy known factual inaccuracies. + +3.5. Application of Additional Terms + +You may choose to offer, and to charge a fee for, warranty, support, +indemnity or liability obligations to one or more recipients of Covered +Software. However, You may do so only on Your own behalf, and not on +behalf of any Contributor. You must make it absolutely clear that any +such warranty, support, indemnity, or liability obligation is offered by +You alone, and You hereby agree to indemnify every Contributor for any +liability incurred by such Contributor as a result of warranty, support, +indemnity or liability terms You offer. You may include additional +disclaimers of warranty and limitations of liability specific to any +jurisdiction. + +4. Inability to Comply Due to Statute or Regulation +--------------------------------------------------- + +If it is impossible for You to comply with any of the terms of this +License with respect to some or all of the Covered Software due to +statute, judicial order, or regulation then You must: (a) comply with +the terms of this License to the maximum extent possible; and (b) +describe the limitations and the code they affect. Such description must +be placed in a text file included with all distributions of the Covered +Software under this License. Except to the extent prohibited by statute +or regulation, such description must be sufficiently detailed for a +recipient of ordinary skill to be able to understand it. + +5. Termination +-------------- + +5.1. The rights granted under this License will terminate automatically +if You fail to comply with any of its terms. However, if You become +compliant, then the rights granted under this License from a particular +Contributor are reinstated (a) provisionally, unless and until such +Contributor explicitly and finally terminates Your grants, and (b) on an +ongoing basis, if such Contributor fails to notify You of the +non-compliance by some reasonable means prior to 60 days after You have +come back into compliance. Moreover, Your grants from a particular +Contributor are reinstated on an ongoing basis if such Contributor +notifies You of the non-compliance by some reasonable means, this is the +first time You have received notice of non-compliance with this License +from such Contributor, and You become compliant prior to 30 days after +Your receipt of the notice. + +5.2. If You initiate litigation against any entity by asserting a patent +infringement claim (excluding declaratory judgment actions, +counter-claims, and cross-claims) alleging that a Contributor Version +directly or indirectly infringes any patent, then the rights granted to +You by any and all Contributors for the Covered Software under Section +2.1 of this License shall terminate. + +5.3. In the event of termination under Sections 5.1 or 5.2 above, all +end user license agreements (excluding distributors and resellers) which +have been validly granted by You or Your distributors under this License +prior to termination shall survive termination. + +************************************************************************ +* * +* 6. Disclaimer of Warranty * +* ------------------------- * +* * +* Covered Software is provided under this License on an "as is" * +* basis, without warranty of any kind, either expressed, implied, or * +* statutory, including, without limitation, warranties that the * +* Covered Software is free of defects, merchantable, fit for a * +* particular purpose or non-infringing. The entire risk as to the * +* quality and performance of the Covered Software is with You. * +* Should any Covered Software prove defective in any respect, You * +* (not any Contributor) assume the cost of any necessary servicing, * +* repair, or correction. This disclaimer of warranty constitutes an * +* essential part of this License. No use of any Covered Software is * +* authorized under this License except under this disclaimer. * +* * +************************************************************************ + +************************************************************************ +* * +* 7. Limitation of Liability * +* -------------------------- * +* * +* Under no circumstances and under no legal theory, whether tort * +* (including negligence), contract, or otherwise, shall any * +* Contributor, or anyone who distributes Covered Software as * +* permitted above, be liable to You for any direct, indirect, * +* special, incidental, or consequential damages of any character * +* including, without limitation, damages for lost profits, loss of * +* goodwill, work stoppage, computer failure or malfunction, or any * +* and all other commercial damages or losses, even if such party * +* shall have been informed of the possibility of such damages. This * +* limitation of liability shall not apply to liability for death or * +* personal injury resulting from such party's negligence to the * +* extent applicable law prohibits such limitation. Some * +* jurisdictions do not allow the exclusion or limitation of * +* incidental or consequential damages, so this exclusion and * +* limitation may not apply to You. * +* * +************************************************************************ + +8. Litigation +------------- + +Any litigation relating to this License may be brought only in the +courts of a jurisdiction where the defendant maintains its principal +place of business and such litigation shall be governed by laws of that +jurisdiction, without reference to its conflict-of-law provisions. +Nothing in this Section shall prevent a party's ability to bring +cross-claims or counter-claims. + +9. Miscellaneous +---------------- + +This License represents the complete agreement concerning the subject +matter hereof. If any provision of this License is held to be +unenforceable, such provision shall be reformed only to the extent +necessary to make it enforceable. Any law or regulation which provides +that the language of a contract shall be construed against the drafter +shall not be used to construe this License against a Contributor. + +10. Versions of the License +--------------------------- + +10.1. New Versions + +Mozilla Foundation is the license steward. Except as provided in Section +10.3, no one other than the license steward has the right to modify or +publish new versions of this License. Each version will be given a +distinguishing version number. + +10.2. Effect of New Versions + +You may distribute the Covered Software under the terms of the version +of the License under which You originally received the Covered Software, +or under the terms of any subsequent version published by the license +steward. + +10.3. Modified Versions + +If you create software not governed by this License, and you want to +create a new license for such software, you may create and use a +modified version of this License if you rename the license and remove +any references to the name of the license steward (except to note that +such modified license differs from this License). + +10.4. Distributing Source Code Form that is Incompatible With Secondary +Licenses + +If You choose to distribute Source Code Form that is Incompatible With +Secondary Licenses under the terms of this version of the License, the +notice described in Exhibit B of this License must be attached. + +Exhibit A - Source Code Form License Notice +------------------------------------------- + + This Source Code Form is subject to the terms of the Mozilla Public + License, v. 2.0. If a copy of the MPL was not distributed with this + file, You can obtain one at http://mozilla.org/MPL/2.0/. + +If it is not possible or desirable to put the notice in a particular +file, then You may include the notice in a location (such as a LICENSE +file in a relevant directory) where a recipient would be likely to look +for such a notice. + +You may add additional accurate notices of copyright ownership. + +Exhibit B - "Incompatible With Secondary Licenses" Notice +--------------------------------------------------------- + + This Source Code Form is "Incompatible With Secondary Licenses", as + defined by the Mozilla Public License, v. 2.0. diff --git a/README.md b/README.md new file mode 100644 --- /dev/null +++ b/README.md @@ -0,0 +1,154 @@ +# prolens + +![Prolens Logo](https://user-images.githubusercontent.com/8126674/95865685-da91b080-0d5e-11eb-91cd-b6a7bae29262.png) + +[![GitHub CI](https://github.com/kowainik/prolens/workflows/CI/badge.svg)](https://github.com/kowainik/prolens/actions) +[![Hackage](https://img.shields.io/hackage/v/prolens.svg?logo=haskell)](https://hackage.haskell.org/package/prolens) +[![MPL-2.0 license](https://img.shields.io/badge/license-MPL--2.0-blue.svg)](LICENSE) + +The `prolens` package is a Haskell library with a __minimal__ and +__lightweight__ implementation of _optics_. __Optic__ is a high-level +concept for values that provide _composable_ access to different parts of +structures. + +Prolens implements the following optics: + +* __Lens__ — composable getters and setters +* __Prism__ — composable constructors and deconstructors +* __Traversal__ — composable data structures visitors + +## Goals + +We created the `prolens` project in pursuit of the following goals: + +1. __Education__. Teach others how to implement and work with + profunctor optics. This also means that some underlying types or + type variables have different unconventional names +2. __Learning__. Explore new concepts ourselves and understand better + abstractions used in the implementation. +3. __Minimalism__. Keep the number of dependencies, features and code + low, but still solve common problems. +4. __Performance__. Despite being minimalist, implement optics so they + are as fast as manual and clumsy pattern matching. +5. __Exploration__. Understand how different modern Haskell features + can work on improving interface and bring new flavour into standard + approaches. Because of this, we implement our own `Profunctor` + typeclass with the + [QuantifiedConstraints](https://downloads.haskell.org/ghc/latest/docs/html/users_guide/glasgow_exts.html#quantified-constraints) + feature, which is not present in any other library at the moment. +6. __Profunctors__. We use profunctor encoding of optics because it + has more elegant design with fewer surprises. + +## Features + +1. __Lightweight__. Only + [base](http://hackage.haskell.org/package/base) + in dependencies. The project itself also has a rather small amount + of code. +2. __Fast__. Despite being lightweight, `prolens` provides a + performant API. We use the + [inspection-testing](https://hackage.haskell.org/package/inspection-testing) + library to guarantee that our implementation of optics compiles to + the same code as plain Haskell getters, record-update syntax and + pattern matching. +3. __Excellent documentation__. The `prolens` library contains a + mini-tutorial on optics, enough to understand how and when to use + basic lenses and prisms. +4. __Beginner-friendly__. The abstractions in the implementation are + hardcore, but our documentation presents the concept in a + beginner-friendly and approachable manner. +5. __Lawful__. We use property-based testing to make sure that laws of + all underlying abstractions are verified. + +## How to use + +`prolens` is compatible with the latest GHC compiler +versions starting from `8.6.5`. + +In order to start using `prolens` in your project, you +will need to set it up with the three easy steps: + +1. Add the dependency on `prolens` in your project's + `.cabal` file. For this, you should modify the `build-depends` + section by adding the name of this library. After the adjustment, + this section could look like this: + + ```haskell + build-depends: base ^>= 4.14 + , prolens ^>= 0.0 + ``` +2. In the module where you wish to use composable getters and setters, + you should add the import: + + ```haskell + import Prolens (Lens', lens, view) + ``` +3. Now you can use the types and functions from the library: + + ```haskell + data User = User + { userName :: String + , userAge :: Int + } + + nameL :: Lens' User String + nameL = lens userName (\u new -> u { userName = new }) + + main :: IO () + main = putStrln $ view nameL (User "Johnny" 27) + ``` + +### Usage with Stack + +If `prolens` is not available on your current Stackage +resolver yet, fear not! You can still use it from Hackage by adding +the following to the `extra-deps` section of your `stack.yaml` file: + +```yaml +extra-deps: + - prolens-0.0.0.0 +``` + +## Comparison to other libraries + +1. [lens](https://hackage.haskell.org/package/lens) + + It is the most mature Haskell library for optics. `lens` provides a + richer interface, but it is heavyweight and based on Van Laarhoven (VL) + encoding of lenses. + +2. [microlens](https://hackage.haskell.org/package/microlens) + + A lightweight implementation of optics compatible with + `lens`. `microlens` is also minimalistic, but it doesn't provide + prisms and is based on VL encoding. + +3. [optics](https://hackage.haskell.org/package/optics) + + The `optics` library uses the profunctor encoding. It provides much + more features than `prolens`, but at the same time it's + heavyweight. Also, `optics` uses an opaque representation of optics + (e.g. they are wrapped in a newtype), which means that they are + composed using the custom operator `%`, while in `prolens` optics + are type aliases to functions and can be easily composed with the + dot `.` operator. + +4. [profunctor-optics](https://hackage.haskell.org/package/profunctor-optics) + + This library is also based on profunctor encoding (as the name + suggests) and provides optics as aliases to functions. But it is + more heavyweight, though it provides more features. + +In addition to this per-library comparison, `prolens` has a few unique +features: + + * Beginner-friendly documentation with usage examples + * Usage of `inspection-testing` to guarantee the performance of + optics + * Property-based tests of lens and typeclasses laws to make sure + that all abstractions behave properly + +## Acknowledgement + + * Edward Kmett for lenses and profunctor typeclasses + * Well-Typed for the implementation of `optics` diff --git a/prolens.cabal b/prolens.cabal new file mode 100644 --- /dev/null +++ b/prolens.cabal @@ -0,0 +1,99 @@ +cabal-version: 2.4 +name: prolens +version: 0.0.0.0 +synopsis: Profunctor-based lightweight implementation of optics +description: + Lightweight and performance implementation of optics — lenses, prisms, traversals. + . + The library uses hardcore abstractions internally, but provides + beginner-friendly, composable and convenient interface for working + with data structures. +homepage: https://github.com/kowainik/prolens +bug-reports: https://github.com/kowainik/prolens/issues +license: MPL-2.0 +license-file: LICENSE +author: Veronika Romashkina, Dmitrii Kovanikov +maintainer: Kowainik +copyright: 2020 Kowainik +category: Data, Optics, Lenses +build-type: Simple +extra-doc-files: README.md + CHANGELOG.md +tested-with: GHC == 8.6.5 + GHC == 8.8.4 + GHC == 8.10.2 + +source-repository head + type: git + location: https://github.com/kowainik/prolens.git + +common common-options + build-depends: base >= 4.12.0.0 && < 4.15 + + ghc-options: -Wall + -Wcompat + -Widentities + -Wincomplete-uni-patterns + -Wincomplete-record-updates + -Wredundant-constraints + if impl(ghc >= 8.2) + ghc-options: -fhide-source-paths + if impl(ghc >= 8.4) + ghc-options: -Wmissing-export-lists + -Wpartial-fields + if impl(ghc >= 8.8) + ghc-options: -Wmissing-deriving-strategies + -fwrite-ide-info + -hiedir=.hie + if impl(ghc >= 8.10) + ghc-options: -Wunused-packages + + default-language: Haskell2010 + default-extensions: ConstraintKinds + DeriveGeneric + DerivingStrategies + GeneralizedNewtypeDeriving + InstanceSigs + KindSignatures + LambdaCase + OverloadedStrings + RecordWildCards + ScopedTypeVariables + StandaloneDeriving + TupleSections + TypeApplications + ViewPatterns + +common common-test + import: common-options + hs-source-dirs: test + ghc-options: -threaded + +library + import: common-options + hs-source-dirs: src + exposed-modules: Prolens + +test-suite prolens-test + import: common-test + type: exitcode-stdio-1.0 + main-is: Spec.hs + + other-modules: Test.Data + Test.Prolens + Test.Prolens.Property + Test.Prolens.Inspection + + build-depends: prolens + , hedgehog >= 1.0.2 && < 2 + , hspec ^>= 2.7.4 + , hspec-hedgehog + , inspection-testing ^>= 0.4 + ghc-options: -rtsopts + -with-rtsopts=-N + +test-suite doctest + import: common-test + type: exitcode-stdio-1.0 + main-is: Doctest.hs + build-depends: doctest ^>= 0.17 diff --git a/src/Prolens.hs b/src/Prolens.hs new file mode 100644 --- /dev/null +++ b/src/Prolens.hs @@ -0,0 +1,989 @@ +{-# OPTIONS_GHC -Wno-redundant-constraints #-} + +{-# LANGUAGE QuantifiedConstraints #-} +{-# LANGUAGE RankNTypes #-} +{-# LANGUAGE TypeFamilies #-} + +{- | +Copyright: (c) 2020 Kowainik +SPDX-License-Identifier: MPL-2.0 +Maintainer: Kowainik + +The @prolens@ package is a Haskell library with a minimal and lightweight +implementation of optics based on 'Profunctor's. __'Optic'__ is a high-level +concept for values that provide composable access to different parts of structures. + +"Prolens" implements the following optics: + + * 'Lens' — composable getters and setters + * 'Prism' — composable constructors and deconstructors + * 'Traversal' — composable data structures visitors + +== Usage + +To use lenses or prisms in your project, you need to add @prolens@ package as +the dependency in the @build-depends@ field of your @.cabal@ file. E.g.: + +@ +build-depends: prolens ^>= 0.0.0.0 +@ + +You should add the import of this module in the place of lenses usage: + +@ +__import__ "Prolens" +@ + +== Creating your own optics + +We show in each section of this module how to create values of each +kind of optics. + +⚠️ __The general crucial rule__ for achieving maximum performance: +always add @\{\-\# INLINE ... \#\-\}@ pragmas to your optics. + +== Typeclasses table + +The below table shows required constraints for each 'Optic': + ++-------------+------------------------------+ +| Optic | Constraints | ++=============+==============================+ +| 'Lens' | @'Strong' p@ | ++-------------+------------------------------+ +| 'Prism' | @'Choice' p@ | ++-------------+------------------------------+ +| 'Traversal' | @('Choice' p, 'Monoidal' p)@ | ++-------------+------------------------------+ + +== Usage table: get, set, modify + +Here is a go-to table on how to use getter, setters and modifiers with different +'Optic's. + ++-------------+------------------+--------------+------------------+------------------+-----------------+-----------------+ +| | get | get operator | set | set operator | modify | modify operator | ++=============+==================+==============+==================+==================+=================+=================+ +| 'Lens' | @'view' l x@ | @x '^.' l@ | @'set' l new x@ | @x & l '.~' new@ | @'over' l f x@ | @x & l '%~' f@ | ++-------------+------------------+--------------+------------------+------------------+-----------------+-----------------+ +| 'Prism' | @'preview' _L x@ | - | @'set' _L new x@ | - | @'over' _L f x@ | - | ++-------------+------------------+--------------+------------------+------------------+-----------------+-----------------+ +| 'Traversal' | @'view' l x@ | - | @'set' l new x@ | - | @'over' l f x@ | - | ++-------------+------------------+--------------+------------------+------------------+-----------------+-----------------+ + +@since 0.0.0.0 +-} + +module Prolens + ( -- * Profunctor typeclass + Profunctor (..) + + -- * Optics + , Optic + + -- * Lenses + -- $lenses + + -- ** Lenses types + , Lens + , Lens' + -- ** Strong typeclass + , Strong (..) + + -- ** Lenses functions + , set + , over + , view + , lens + + -- ** Lenses operators + , (^.) + , (.~) + , (%~) + + -- ** Standard lenses + , fstL + , sndL + + -- * Prisms + -- $prisms + + -- ** Prism types + , Prism + , Prism' + -- ** Choice typeclass + , Choice (..) + + -- ** Prism functions + , prism + , prism' + , preview + + -- ** Standard Prisms + , _Just + , _Left + , _Right + + -- * Traversals + + -- ** Traversal types + , Traversal + -- ** Monoidal typeclass + , Monoidal (..) + + -- ** Traversal functions + , traverseOf + + -- ** Standard traversals + , eachPair + , eachMaybe + , eachList + + -- * Internal data types + , Forget (..) + , Fun (..) + ) where + +import Control.Applicative (Const (..), liftA2) +import Data.Coerce (coerce) +import Data.Monoid (First (..)) + +-- $setup +-- >>> import Data.Function ((&)) + + +{- | The type @p@ is called 'Profunctor' and it means, that a value of +type @p in out@ takes a value of type @in@ as an argument (input) and +outputs a value of type @out@. 'Profunctor' allows mapping of inputs +and outputs. + +@ + +----> Result input + | + | +--> Original profunctor + | +-> Original input | + + + + +dimap :: (in2 -> in1) -> (out1 -> out2) -> p in1 out1 -> p in2 out2 + + + + | +-> Result output + | + +-> Original output +@ + +Speaking in terms of other abstractions, 'Profunctor' is +'Data.Functor.Contravariant.Contravariant' in the first type argument +(type variable @in@) and 'Functor' in the second type argument (type +variable @out@). + +Moreover, @p in@ must have 'Functor' instance first to implement the +'Profunctor' instance. This required using @QuantifiedConstraints@. + +@ + Contravariant <---+ + | + +-+-+ + + + +(forall a . Functor (p a)) => Profunctor p a b + + + + + | | | + +--> Quantified constraint +++ + | + Functor <--+ +@ + +Instances of 'Profunctor' should satisfy the following laws: + +* __Identity:__ @'dimap' 'id' 'id' ≡ 'id'@ +* __Composition:__ @'dimap' (inAB . inBC) (outYZ . outXY) ≡ 'dimap' outBC outYZ . 'dimap' outAB outXY@ + +@since 0.0.0.0 +-} +-- type Profunctor :: (Type -> Type -> Type) -> Constraint +class (forall a . Functor (p a)) => Profunctor p where + dimap + :: (in2 -> in1) -- ^ Map input + -> (out1 -> out2) -- ^ Map output + -> p in1 out1 -- ^ Take @in1@ as input and return @out1@ + -> p in2 out2 -- ^ Take @in2@ as input and return @out2@ + +-- | @since 0.0.0.0 +instance Profunctor (->) where + dimap :: (in2 -> in1) -> (out1 -> out2) -> (in1 -> out1) -> (in2 -> out2) + dimap in21 out12 f = out12 . f . in21 + {-# INLINE dimap #-} + +{- | @'Fun' m a b@ is a wrapper for function @a -> m b@. + +@since 0.0.0.0 +-} +newtype Fun m a b = Fun + { unFun :: a -> m b + } + +-- | @since 0.0.0.0 +instance Functor m => Functor (Fun m x) where + fmap :: (a -> b) -> Fun m x a -> Fun m x b + fmap f (Fun xma) = Fun (fmap f . xma) + {-# INLINE fmap #-} + +-- | @since 0.0.0.0 +instance Functor m => Profunctor (Fun m) where + dimap :: (in2 -> in1) -> (out1 -> out2) -> Fun m in1 out1 -> Fun m in2 out2 + dimap in21 out12 (Fun f) = Fun (fmap out12 . f . in21) + {-# INLINE dimap #-} + +{- | 'Strong' is a 'Profunctor' that can be lifted to take a pair as +an input and return a pair. + +The second element of a pair (variable of type @c@) can be of any +type, and you can decide what type it should be. This is convenient +for implementing various functions. E.g. 'lens' uses this fact. + +@since 0.0.0.0 +-} +class Profunctor p => Strong p where + first :: p a b -> p (a, c) (b, c) + second :: p a b -> p (c, a) (c, b) + +-- | @since 0.0.0.0 +instance Strong (->) where + first :: (a -> b) -> (a, c) -> (b, c) + first ab (a, c) = (ab a, c) + {-# INLINE first #-} + + second :: (a -> b) -> (c, a) -> (c, b) + second ab (c, a) = (c, ab a) + {-# INLINE second #-} + +-- | @since 0.0.0.0 +instance (Functor m) => Strong (Fun m) where + first :: Fun m a b -> Fun m (a, c) (b, c) + first (Fun amb) = Fun (\(a, c) -> fmap (, c) (amb a)) + {-# INLINE first #-} + + second :: Fun m a b -> Fun m (c, a) (c, b) + second (Fun amb) = Fun (\(c, a) -> fmap (c,) (amb a)) + {-# INLINE second #-} + +{- | 'Choice' is a 'Profunctor' that can be lifted to work with +'Either' given input or some other value. + +The other element of 'Either' (variable of type @c@) can be of any +type, and you can decide what type it should be. This is convenient +for implementing various functions. E.g. 'prism' uses this fact. + +@since 0.0.0.0 +-} +class Profunctor p => Choice p where + left :: p a b -> p (Either a c) (Either b c) + right :: p a b -> p (Either c a) (Either c b) + +-- | @since 0.0.0.0 +instance Choice (->) where + left :: (a -> b) -> Either a c -> Either b c + left ab = \case + Left a -> Left $ ab a + Right c -> Right c + {-# INLINE left #-} + + right :: (a -> b) -> Either c a -> Either c b + right ab = \case + Right a -> Right $ ab a + Left c -> Left c + {-# INLINE right #-} + +-- | @since 0.0.0.0 +instance (Applicative m) => Choice (Fun m) where + left :: Fun m a b -> Fun m (Either a c) (Either b c) + left (Fun amb)= Fun $ \eitherAc -> case eitherAc of + Left a -> Left <$> amb a + Right c -> pure $ Right c + {-# INLINE left #-} + + right :: Fun m a b -> Fun m (Either c a) (Either c b) + right (Fun amb)= Fun $ \eitherCa -> case eitherCa of + Right a -> Right <$> amb a + Left c -> pure $ Left c + {-# INLINE right #-} + +{- | 'Monoidal' is 'Strong' 'Profunctor' that can be appended. It is +similar to 'Monoid's but for higher-kinded types. + +@since 0.0.0.0 +-} +class Strong p => Monoidal p where + pappend :: p a b -> p c d -> p (a, c) (b, d) + pempty :: p a a + +-- | @since 0.0.0.0 +instance Monoidal (->) where + pappend :: (a -> b) -> (c -> d) -> (a, c) -> (b, d) + pappend ab cd (a, c) = (ab a, cd c) + {-# INLINE pappend #-} + + pempty :: a -> a + pempty = id + {-# INLINE pempty #-} + +-- | @since 0.0.0.0 +instance (Applicative m) => Monoidal (Fun m) where + pappend :: Fun m a b -> Fun m c d -> Fun m (a, c) (b, d) + pappend (Fun amb) (Fun cmd) = Fun (\(a, c) -> liftA2 (,) (amb a) (cmd c)) + {-# INLINE pappend #-} + + pempty :: Fun m a a + pempty = Fun (pure . id) + {-# INLINE pempty #-} + +{- | 'Optic' takes a connection from @a@ to @b@ (represented as a +value of type @p a b@) and returns a connection from @source@ to +@target@ (represented as a value of type @p source target@). + +@ + +---> Profunctor + | + | +----> Final input + | | + | | +-> Final output + | | | + + + + +type Optic p source target a b + + + + | | + Given input <--+ | + | + Given output <-------+ +@ + +@since 0.0.0.0 +-} +type Optic p source target a b = p a b -> p source target + + +{- $lenses + +== Example + +To understand better how to use this library lets look at some simple example. +Let's say we have the user and address data types in our system: + +>>> :{ +data Address = Address + { addressCountry :: String + , addressCity :: String + , addressIndex :: String + } deriving (Show) +:} + +>>> :{ +data User = User + { userName :: String + , userAge :: Int + , userAddress :: Address + } deriving (Show) +:} + +We can easily get fields of the @User@ and @Address@ types, but +setting values is inconvenient (especially for nested records). To +solve this problem, we can use lenses — composable getters and +setters. 'Lens' is a value, so we need to define lenses for fields of +our data types first. + +To create the lens for the @userName@ field we can use 'lens' function and +manually writing getter and setter function: + +>>> :{ +nameL :: Lens' User String +nameL = lens getter setter + where + getter :: User -> String + getter = userName + setter :: User -> String -> User + setter user newName = user {userName = newName} +:} + +In this manner, we can create other lenses for our @User@ data type. +Usually, lenses are one-liners, and we can define them easily using lambda-functions. + +>>> :{ +ageL :: Lens' User Int +ageL = lens userAge (\u new -> u {userAge = new}) +:} + +>>> :{ +addressL :: Lens' User Address +addressL = lens userAddress (\u new -> u {userAddress = new}) +:} + +We want to have lenses for accessing @Adress@ fields inside @User@, so we want to have the following values: + +@ +countryL :: 'Lens'' User 'String' +cityL :: 'Lens'' User 'String' +indexL :: 'Lens'' User 'String' +@ + +/Note:/ for lenses as @countryL@, @cityL@ etc., we are using composition of the +lenses for the @userAddress@ field. If we have + +>>> :{ +addressCityL :: Lens' Address String +addressCityL = lens addressCity (\a new -> a {addressCity = new}) +:} + +then + +>>> cityL = addressL . addressCityL + +Let's say we have some sample user + +>>> :{ +address = Address + { addressCountry = "UK" + , addressCity = "London" + , addressIndex = "XXX" + } +user :: User +user = User + { userName = "John" + , userAge = 42 + , userAddress = address + } +:} + +To view the fields of the User data type we can use 'view' or '^.' + +>>> view ageL user +42 +>>> user ^. cityL +"London" + +If we want to change any of the user's data, we should use 'set' or '.~' + +>>> set nameL "Johnny" user +User {userName = "Johnny", userAge = 42, userAddress = Address {addressCountry = "UK", addressCity = "London", addressIndex = "XXX"}} +>>> user & cityL .~ "Bristol" +User {userName = "John", userAge = 42, userAddress = Address {addressCountry = "UK", addressCity = "Bristol", addressIndex = "XXX"}} + +'over' or '%~' operator could be useful when, for example, you want to increase the age by one on the user's birthday: + +>>> over ageL succ user +User {userName = "John", userAge = 43, userAddress = Address {addressCountry = "UK", addressCity = "London", addressIndex = "XXX"}} +>>> user & ageL %~ succ +User {userName = "John", userAge = 43, userAddress = Address {addressCountry = "UK", addressCity = "London", addressIndex = "XXX"}} +-} + +{- | 'Lens' represents composable getters and setters. + +'Lens' is an @'Optic' p@ with the 'Strong' constraint on the @p@ type variable. + +@ + +---> Current object + | + | +-> Final object + | | + + + +type Lens source target a b + + + + | | + Current field <--+ | + | + Final field <-------+ +@ + +@since 0.0.0.0 +-} +type Lens source target a b = forall p . Strong p => Optic p source target a b + +{- | The monomorphic lenses which don't change the type of the container (or of +the value inside). It has a 'Strong' constraint, and it can be used whenever a +getter or a setter is needed. + + * @a@ is the type of the value inside of structure + * @source@ is the type of the whole structure + +For most use-cases it's enought to use this 'Lens'' instead of more general 'Lens'. + +@since 0.0.0.0 +-} +type Lens' source a = Lens source source a a + +{- | Sets the given value to the structure using a setter. + +@since 0.0.0.0 +-} +set :: (p ~ (->)) + => Optic p source target a b -- ^ 'Optic' that can be lens + -> b -- ^ Value to set + -> source -- ^ Object where we want to set value + -> target -- ^ Resulting object with @b@ set +set abst = abst . const +{-# INLINE set #-} + +{- | Applies the given function to the target. + +@since 0.0.0.0 +-} +over + :: (p ~ (->)) + => Optic p source target a b -- ^ 'Optic' that can be lens + -> (a -> b) -- ^ Field modification function + -> source -- ^ Object where we want to set value + -> target -- ^ Resulting object with the modified field +over = id +{-# INLINE over #-} + +{- | Gets a value out of a structure using a getter. + +@since 0.0.0.0 +-} +view + :: (p ~ Fun (Const a)) + => Optic p source target a b -- ^ 'Optic' that can be lens + -> source -- ^ Object from which we want to get value + -> a -- ^ Field of @source@ +view opt = coerce (opt (Fun Const)) +{-# INLINE view #-} +-- view opt = getConst . unFun (opt (Fun Const)) +-- opt :: Fun (Const a) a b -> Fun (Const a) s t +-- opt :: (a -> Const a b) -> ( s -> Const a t) + +{- | Creates 'Lens' from the getter and setter. + +@since 0.0.0.0 +-} +lens + :: (source -> a) -- ^ Getter + -> (source -> b -> target) -- ^ Setter + -> Lens source target a b +lens getter setter = dimap (\s -> (s, getter s)) (uncurry setter) . second +{-# INLINE lens #-} + +{- | The operator form of 'view' with the arguments flipped. + +@since 0.0.0.0 +-} +infixl 8 ^. +(^.) :: source -> Lens' source a -> a +s ^. l = view l s +{-# INLINE (^.) #-} + +{- | The operator form of 'set'. + +@since 0.0.0.0 +-} +infixr 4 .~ +(.~) :: Lens' source a -> a -> source -> source +(.~) = set +{-# INLINE (.~) #-} + +{- | The operator form of 'over'. + +@since 0.0.0.0 +-} +infixr 4 %~ +(%~) :: Lens' source a -> (a -> a) -> source -> source +(%~) = over +{-# INLINE (%~) #-} + +{- | 'Lens'' for a tuple on the first argument. + +>>> view fstL (42, "str") +42 + +@since 0.0.0.0 +-} +fstL :: Lens (a, c) (b, c) a b +fstL = lens fst $ \(_, b) new -> (new, b) +{-# INLINE fstL #-} + +{- | 'Lens'' for a tuple on the second argument. + +>>> view sndL (42, "Hello") +"Hello" + +@since 0.0.0.0 +-} +sndL :: Lens (x, a) (x, b) a b +sndL = lens snd $ \(a, _) new -> (a, new) +{-# INLINE sndL #-} + +{- $prisms +Prisms work with sum types. + +== Example + +Let's say we have the user data type in our system: + +>>> :{ +data Address = Address + { addressCountry :: String + , addressCity :: String + } deriving (Show) +:} + +>>> :{ +data Payload + = NamePayload String + | IdPayload Int + | AddressPayload Address + deriving (Show) +:} + +To create the prism for each constructor we can use 'prism'' function and +manually writing getter and setter function: + +/NOTE:/ The naming convention for prisms is the following: + +@ +_ConstructorName +@ + +>>> :{ +_NamePayload :: Prism' Payload String +_NamePayload = prism' construct match + where + match :: Payload -> Maybe String + match p = case p of + NamePayload name -> Just name + _otherPayload -> Nothing + construct :: String -> Payload + construct = NamePayload +:} + +In this manner, we can create other prisms for our @Payload@ data type. + +>>> :{ +_IdPayload :: Prism' Payload Int +_IdPayload = prism' IdPayload $ \p -> case p of + IdPayload i -> Just i + _otherPayload -> Nothing +:} + +>>> :{ +_AddressPayload :: Prism' Payload Address +_AddressPayload = prism' AddressPayload $ \p -> case p of + AddressPayload a -> Just a + _otherPayload -> Nothing +:} + +Let's say we have some sample payload + +>>> :{ +payloadName :: Payload +payloadName = NamePayload "Some name" +:} + +To view the fields of the @Payload@ data type we can use 'preview' + +>>> preview _NamePayload payloadName +Just "Some name" +>>> preview _IdPayload payloadName +Nothing + +If we want to change any of the data, we should use 'set' or '.~' (just like in lenses) + +>>> set _NamePayload "Johnny" payloadName +NamePayload "Johnny" +>>> set _IdPayload 3 payloadName +NamePayload "Some name" + +Note, that you can easily compose lenses and prisms together: + +>>> :{ +address = Address + { addressCountry = "UK" + , addressCity = "London" + } +:} + +>>> :{ +addressCityL :: Lens' Address String +addressCityL = lens addressCity (\a new -> a {addressCity = new}) +:} + +>>> :{ +payloadAddress :: Payload +payloadAddress = AddressPayload address +:} + +>>> set _AddressPayload (address & addressCityL .~ "Bristol") payloadAddress +AddressPayload (Address {addressCountry = "UK", addressCity = "Bristol"}) +-} + +{- | 'Prism' represents composable constructors and deconstructors. + +'Prism' is an @'Optic' p@ with 'Choice' constraint on the @p@ type +variable. + +@ + +---> Current object + | + | +-> Final object + | | + + + + type Prism source target a b + + + + | | + Field in current constructor <--+ | + | +Field in final constructor <-------+ +@ + +@since 0.0.0.0 +-} +type Prism source target a b = forall p . Choice p => Optic p source target a b + +{- | The monomorphic prisms which don't change the type of the container (or of +the value inside). + + * @a@ is the value inside the particular constructor + * @source@ is some sum type + +@since 0.0.0.0 +-} +type Prism' source a = Prism source source a a + +{- | Newtype around function @a -> r@. It's called /forget/ because it +forgets about its last type variable. + +@since 0.0.0.0 +-} +newtype Forget r a b = Forget + { unForget :: a -> r + } + +-- | @since 0.0.0.0 +instance Functor (Forget r x) where + fmap :: (a -> b) -> Forget r x a -> Forget r x b + fmap _ = coerce + +-- | @since 0.0.0.0 +instance Profunctor (Forget r) where + dimap :: (a -> b) -> (c -> d) -> Forget r b c -> Forget r a d + dimap ab _cd (Forget br) = Forget (br . ab) + {-# INLINE dimap #-} + +-- | @since 0.0.0.0 +instance Strong (Forget r) where + first :: Forget r a b -> Forget r (a, c) (b, c) + first (Forget ar) = Forget (ar . fst) + {-# INLINE first #-} + + second :: Forget r a b -> Forget r (c, a) (c, b) + second (Forget ar) = Forget (ar . snd) + {-# INLINE second #-} + +-- | @since 0.0.0.0 +instance Monoid r => Choice (Forget r) where + left :: Forget r a b -> Forget r (Either a c) (Either b c) + left (Forget ar) = Forget (either ar (const mempty)) + {-# INLINE left #-} + + right :: Forget r a b -> Forget r (Either c a) (Either c b) + right (Forget ar) = Forget (either (const mempty) ar) + {-# INLINE right #-} + +-- | @since 0.0.0.0 +instance (Monoid r) => Monoidal (Forget r) where + pappend :: Forget r a b -> Forget r c d -> Forget r (a, c) (b, d) + pappend (Forget ar) (Forget cr) = Forget (\(a, c) -> ar a <> cr c) + {-# INLINE pappend #-} + + pempty :: Forget r a a + pempty = Forget (const mempty) + {-# INLINE pempty #-} + +{- | Match a value from @source@ type. + +@since 0.0.0.0 +-} +preview + :: forall a source p + . (p ~ Forget (First a)) + => Optic p source source a a -- ^ 'Optic' that can be prism + -> source -- ^ Object (possible sum type) + -> Maybe a -- ^ Value of type @a@ from a specific constructor +preview paapss = coerce (paapss wrap) + where + wrap :: Forget (First a) a a + wrap = coerce @(a -> Maybe a) @(Forget (First a) a a) Just + {-# INLINE wrap #-} +{-# INLINE preview #-} +-- preview paapss = getFirst . unForget (paapss (Forget (First . Just))) +-- paapss :: Forget (First a) a a -> Forget (First a) source source +-- paapss :: (a -> First a) -> source -> First a +-- paapss :: (a -> Maybe a) -> source -> Maybe a + +{- | Create 'Prism' from constructor and matching function. + +@since 0.0.0.0 +-} +prism + :: (b -> target) -- ^ Constructor + -> (source -> Either target a) -- ^ Matching function + -> Prism source target a b +-- prism :: (b -> target) -> (source -> Either target a) -> p a b -> p source target +prism ctor match = dimap match (either id ctor) . right +{-# INLINE prism #-} + +{- | Create monomorphic 'Prism'' from constructor and matching function. + +@since 0.0.0.0 +-} +prism' + :: (a -> source) -- ^ Constructor + -> (source -> Maybe a) -- ^ Matching function + -> Prism' source a +prism' ctor match = prism ctor (\s -> maybe (Left s) Right $ match s) +{-# INLINE prism' #-} + +{- | 'Prism' for a 'Just' of 'Maybe'. + +>>> preview _Just (Just 42) +Just 42 + +>>> preview _Just Nothing +Nothing + +@since 0.0.0.0 +-} +_Just :: Prism (Maybe a) (Maybe b) a b +_Just = prism Just $ \case + Just a -> Right a + Nothing -> Left Nothing +{-# INLINE _Just #-} + + +{- | 'Prism' for a 'Left' of 'Either'. + +>>> preview _Left (Left 42) +Just 42 + +>>> preview _Left (Right "Hello") +Nothing + +@since 0.0.0.0 +-} +_Left :: Prism (Either a x) (Either b x) a b +_Left = prism Left $ \case + Left l -> Right l + Right r -> Left $ Right r +{-# INLINE _Left #-} + +{- | 'Prism' for a 'Left' of 'Either'. + +>>> preview _Right (Left 42) +Nothing + +>>> preview _Right (Right "Hello") +Just "Hello" + +@since 0.0.0.0 +-} +_Right :: Prism (Either x a) (Either x b) a b +_Right = prism Right $ \case + Right a -> Right a + Left x -> Left $ Left x +{-# INLINE _Right #-} + + +{- | 'Traversal' provides composable ways to visit different parts of +a data structure. + +'Traversal' is an @'Optic' p@ with the 'Choice' and 'Monoidal' +constraints on the @p@ type variable. + +@ + +---> Current collection + | + | +-> Final collection + | | + + + +type Traversal source target a b + + + + | | + Current element <--+ | + | + Final element <-------+ +@ + +@since 0.0.0.0 +-} +type Traversal source target a b + = forall p + . (Choice p, Monoidal p) + => Optic p source target a b + +{- | Traverse a data structure using given 'Traversal'. + +>>> traverseOf eachPair putStrLn ("Hello", "World!") +Hello +World! +((),()) + +@since 0.0.0.0 +-} +traverseOf + :: (Applicative f, p ~ Fun f) + => Optic p source target a b -- ^ 'Optic' that can be a traversal + -> (a -> f b) -- ^ Traversing function + -> source -- ^ Data structure to traverse + -> f target -- ^ Traversing result +traverseOf pabPst aFb = unFun (pabPst (Fun aFb)) +-- pabPst :: Fun f a b -> Fun f source target +-- pabPst :: (a -> f b) -> Fun f source target + +{- | 'Traversal' for a pair of same type elements. + +>>> over eachPair (+ 1) (3, 7) +(4,8) + +@since 0.0.0.0 +-} +eachPair :: Traversal (a, a) (b, b) a b +eachPair pab = pappend pab pab + +{- | 'Traversal' for a 'Maybe'. + +>>> over eachMaybe (+ 1) (Just 3) +Just 4 +>>> over eachMaybe (+ 1) Nothing +Nothing + +@since 0.0.0.0 +-} +eachMaybe :: Traversal (Maybe a) (Maybe b) a b +eachMaybe pab = dimap maybeToEither eitherToMaybe (left pab) + where + maybeToEither :: Maybe a -> Either a () + maybeToEither = \case + Just a -> Left a + Nothing -> Right () + + eitherToMaybe :: Either a () -> Maybe a + eitherToMaybe = \case + Left a -> Just a + Right () -> Nothing + +{- | 'Traversal' for lists. + +>>> over eachList (+ 1) [1..5] +[2,3,4,5,6] +>>> over eachList (+ 1) [] +[] + +@since 0.0.0.0 +-} +eachList :: Traversal [a] [b] a b +eachList pab = dimap listToEither eitherToList $ left $ pappend pab (eachList pab) + where + listToEither :: [a] -> Either (a, [a]) () + listToEither = \case + [] -> Right () + x:xs -> Left (x, xs) + + eitherToList :: Either (a, [a]) () -> [a] + eitherToList = \case + Right () -> [] + Left (x, xs) -> x:xs diff --git a/test/Doctest.hs b/test/Doctest.hs new file mode 100644 --- /dev/null +++ b/test/Doctest.hs @@ -0,0 +1,15 @@ +module Main (main) where + +import Test.DocTest (doctest) + + +main :: IO () +main = doctest + $ "-XLambdaCase" + : "-XInstanceSigs" + : "-XScopedTypeVariables" + : "-XTupleSections" + : "-XTypeApplications" + : + [ "src/Prolens.hs" + ] diff --git a/test/Spec.hs b/test/Spec.hs new file mode 100644 --- /dev/null +++ b/test/Spec.hs @@ -0,0 +1,15 @@ +module Main (main) where + +import Test.Hspec (hspec) + +import Test.Prolens (unitSpecs) +import Test.Prolens.Inspection (inspectionSpecs) +import Test.Prolens.Property (lensPropertySpecs, typeclassesPropertySpecs) + + +main :: IO () +main = hspec $ do + unitSpecs + inspectionSpecs + lensPropertySpecs + typeclassesPropertySpecs diff --git a/test/Test/Data.hs b/test/Test/Data.hs new file mode 100644 --- /dev/null +++ b/test/Test/Data.hs @@ -0,0 +1,131 @@ +module Test.Data + ( -- * Lenses + Haskeller (..) + , nameL + , knowledgeL + + , Knowledge (..) + , syntaxL + + , me + + -- * Prisms + , Grade (..) + , _Mark + + , gradeMark + , gradeOther + + -- * Generators + , genFun + , genFunction + , genHaskeller + , genInt + , genKnowledge + , genName + ) where + +import Test.Hspec.Hedgehog (MonadGen) + +import Prolens (Fun (..), Lens', Prism', lens, prism') + +import qualified Hedgehog.Gen as Gen +import qualified Hedgehog.Range as Range + + +data Haskeller = Haskeller + { haskellerName :: String + , haskellerExperience :: Int + , haskellerKnowledge :: Knowledge + } deriving stock (Show, Eq) + +data Knowledge = Knowledge + { kSyntax :: Bool + , kMonads :: Bool + , kLens :: Bool + , kTypeLevelMagic :: Bool + , kNix :: Bool + } deriving stock (Show, Eq) + +me :: Haskeller +me = Haskeller + { haskellerName = "Veronika" + , haskellerExperience = 2 + , haskellerKnowledge = Knowledge + { kSyntax = True + , kMonads = True + , kLens = True + , kTypeLevelMagic = True + , kNix = False + } + } + +nameL :: Lens' Haskeller String +nameL = lens haskellerName (\h new -> h { haskellerName = new }) +{-# INLINE nameL #-} + +knowledgeL :: Lens' Haskeller Knowledge +knowledgeL = lens haskellerKnowledge (\h new -> h { haskellerKnowledge = new }) +{-# INLINE knowledgeL #-} + +syntaxL :: Lens' Knowledge Bool +syntaxL = lens kSyntax (\k new -> k { kSyntax = new }) +{-# INLINE syntaxL #-} + +data Grade + = Mark Int + | Other String + deriving stock (Show, Eq) + +_Mark :: Prism' Grade Int +_Mark = prism' Mark $ \case + Mark a -> Just a + _other -> Nothing +{-# INLINE _Mark #-} + +gradeMark :: Grade +gradeMark = Mark 5 + +gradeOther :: Grade +gradeOther = Other "Satisfactory" + +-- Generators + +genKnowledge :: (MonadGen m) => m Knowledge +genKnowledge = do + kSyntax <- Gen.bool + kMonads <- Gen.bool + kLens <- Gen.bool + kTypeLevelMagic <- Gen.bool + kNix <- Gen.bool + pure Knowledge{..} + +genHaskeller :: (MonadGen m) => m Haskeller +genHaskeller = do + haskellerName <- genName + haskellerExperience <- Gen.int $ Range.linear 0 50 + haskellerKnowledge <- genKnowledge + pure Haskeller{..} + +genName :: MonadGen m => m String +genName = Gen.string (Range.linear 1 50) Gen.alphaNum + +genInt :: MonadGen m => m Int +genInt = Gen.enumBounded + +genFunction :: MonadGen m => m (Int -> Int) +genFunction = genInt >>= \n -> Gen.element + [ id + , const n + , (+ n) + , (* n) + , subtract n + , \x -> if x >= n then 1 else 0 + ] + +genFun :: MonadGen m => m (Fun Maybe Int Int) +genFun = genFunction >>= \f -> Gen.element $ map Fun + [ Just + , const Nothing + , Just . f + ] diff --git a/test/Test/Prolens.hs b/test/Test/Prolens.hs new file mode 100644 --- /dev/null +++ b/test/Test/Prolens.hs @@ -0,0 +1,43 @@ +module Test.Prolens + ( unitSpecs + ) where + +import Data.Function ((&)) +import Test.Hspec (Spec, describe, it, shouldBe) + +import Prolens (preview, set, view, (.~), (^.)) +import Test.Data (Grade (..), gradeMark, gradeOther, me, nameL, _Mark) + + +unitSpecs :: Spec +unitSpecs = describe "Prolens unit tests" $ do + lensSpecs + prismSpecs + + +lensSpecs :: Spec +lensSpecs = describe "Lenses" $ do + describe "getter" $ do + it "should get name" $ + view nameL me `shouldBe` "Veronika" + it "should get name with ^." $ + (me ^. nameL) `shouldBe` "Veronika" + describe "setter" $ do + it "should set name" $ + view nameL (set nameL "Dmitrii" me) `shouldBe` "Dmitrii" + it "should set name with .~" $ + (me & nameL .~ "Dmitrii") ^. nameL `shouldBe` "Dmitrii" + + +prismSpecs :: Spec +prismSpecs = describe "Prisms" $ do + describe "preview" $ do + it "should get mark" $ + preview _Mark gradeMark `shouldBe` Just 5 + it "should not get mark" $ + preview _Mark gradeOther `shouldBe` Nothing + describe "set" $ do + it "should get mark" $ + set _Mark 4 gradeMark `shouldBe` Mark 4 + it "should not get mark" $ + set _Mark 4 gradeOther `shouldBe` gradeOther diff --git a/test/Test/Prolens/Inspection.hs b/test/Test/Prolens/Inspection.hs new file mode 100644 --- /dev/null +++ b/test/Test/Prolens/Inspection.hs @@ -0,0 +1,87 @@ +{-# LANGUAGE TemplateHaskell #-} + +{- | Performance tests for @prolens@. Uses the @inspection-testing@ +library to make sure that lenses are as efficient as manual record +getters and update syntax. +-} + +module Test.Prolens.Inspection + ( inspectionSpecs + ) where + +import Test.Hspec (Spec, describe, it, shouldSatisfy, xit) +import Test.Inspection (Result (..), hasNoTypeClasses, inspectTest, (===)) + +import Prolens (preview, set, view) +import Test.Data (Grade (..), Haskeller (..), Knowledge (..), _Mark, knowledgeL, nameL, syntaxL) + + +setNameViaLens :: Haskeller -> Haskeller +setNameViaLens = set nameL "Dmitrii" + +setNameManually :: Haskeller -> Haskeller +setNameManually h = h { haskellerName = "Dmitrii" } + +getNameViaLens :: Haskeller -> String +getNameViaLens = view nameL + +getNameManually :: Haskeller -> String +getNameManually (Haskeller name _ _) = name + +setSyntaxViaLens :: Haskeller -> Haskeller +setSyntaxViaLens = set (knowledgeL . syntaxL) True + +setSyntaxManually :: Haskeller -> Haskeller +setSyntaxManually h = h { haskellerKnowledge = (haskellerKnowledge h) { kSyntax = True } } + +getSyntaxViaLens :: Haskeller -> Bool +getSyntaxViaLens = view (knowledgeL . syntaxL) + +getSyntaxManually :: Haskeller -> Bool +getSyntaxManually (Haskeller _ _ (Knowledge syntax _ _ _ _)) = syntax + +inspectionSpecs :: Spec +inspectionSpecs = describe "Performance Inspection Testing" $ do + lensSpecs + prismSpecs + +lensSpecs :: Spec +lensSpecs = describe "Lens" $ do + describe "set" $ do + it "setting single via lens is efficient as manual record update" $ + $(inspectTest $ 'setNameViaLens === 'setNameManually) `shouldSatisfy` isSuccess + it "setting single via lens doesn't have intermediate typeclasses" $ + $(inspectTest $ hasNoTypeClasses 'setNameViaLens) `shouldSatisfy` isSuccess + it "setting composition via lens is efficient as manual record update" $ + $(inspectTest $ 'setSyntaxViaLens === 'setSyntaxManually) `shouldSatisfy` isSuccess + it "setting composition via lens doesn't have intermediate typeclasses" $ + $(inspectTest $ hasNoTypeClasses 'setSyntaxViaLens) `shouldSatisfy` isSuccess + describe "view" $ do + it "getting single via lens is efficient as plain record function" $ + $(inspectTest $ 'getNameViaLens === 'getNameManually) `shouldSatisfy` isSuccess + it "getting single via lens doesn't have intermediate typeclasses" $ + $(inspectTest $ hasNoTypeClasses 'getNameViaLens) `shouldSatisfy` isSuccess + it "getting composition via lens is efficient as plain record function" $ + $(inspectTest $ 'getSyntaxViaLens === 'getSyntaxManually) `shouldSatisfy` isSuccess + it "getting composition via lens doesn't have intermediate typeclasses" $ + $(inspectTest $ hasNoTypeClasses 'getSyntaxViaLens) `shouldSatisfy` isSuccess + +matchMarkPrism :: Grade -> Maybe Int +matchMarkPrism = preview _Mark + +matchMarkManual :: Grade -> Maybe Int +matchMarkManual grade = case grade of + Mark n -> Just n + _other -> Nothing + +prismSpecs :: Spec +prismSpecs = describe "Prism" $ do + describe "preview" $ do + xit "preview _Ctor x ≡ case (Ctor _) of" $ + $(inspectTest $ 'matchMarkPrism === 'matchMarkManual) `shouldSatisfy` isSuccess + +-- Helper functions + +isSuccess :: Result -> Bool +isSuccess (Success _) = True +isSuccess (Failure _) = False diff --git a/test/Test/Prolens/Property.hs b/test/Test/Prolens/Property.hs new file mode 100644 --- /dev/null +++ b/test/Test/Prolens/Property.hs @@ -0,0 +1,68 @@ +module Test.Prolens.Property + ( lensPropertySpecs + , typeclassesPropertySpecs + ) where + +import Test.Hspec (Spec, describe, it) +import Test.Hspec.Hedgehog (PropertyT, forAll, forAllWith, hedgehog, (===)) + +import Prolens +import Test.Data (genFun, genFunction, genHaskeller, genInt, genName, nameL) + + +lensPropertySpecs :: Spec +lensPropertySpecs = describe "Lens Laws" $ do + it "view lens (set lens value source) ≡ value" $ hedgehog $ do + source <- forAll genHaskeller + value <- forAll genName + view nameL (set nameL value source) === value + it "set lens (view lens source) source ≡ source" $ hedgehog $ do + source <- forAll genHaskeller + set nameL (view nameL source) source === source + it "set lens valueNew (set lens value source) ≡ set lens valueNew source" $ hedgehog $ do + source <- forAll genHaskeller + value <- forAll genName + valueNew <- forAll genName + set nameL valueNew (set nameL value source) === set nameL valueNew source + +typeclassesPropertySpecs :: Spec +typeclassesPropertySpecs = describe "Class Laws" -- $ do + profunctorsSpec + +profunctorsSpec :: Spec +profunctorsSpec = describe "Profunctor" $ do + describe "(->)" $ do + it "Identity: dimap id id ≡ id" $ hedgehog $ do + f <- forAllWith (const "f") genFunction + x <- forAll genInt + dimap id id f x === f x + it "Composition: dimap (ab . bc) (yz . xy) ≡ dimap bc yz . dimap ab xy" $ hedgehog $ do + + f <- forAllWith (const "f") genFunction + ab <- forAllWith (const "ab") genFunction + bc <- forAllWith (const "bc") genFunction + xy <- forAllWith (const "xy") genFunction + yz <- forAllWith (const "xy") genFunction + + n <- forAll genInt + dimap (ab . bc) (yz . xy) f n === (dimap bc yz . dimap ab xy) f n + describe "Fun" $ do + it "Identity: dimap id id ≡ id" $ hedgehog $ do + f <- forAllWith (const "f") genFun + eqFun (dimap id id f) f + it "Composition: dimap (ab . bc) (yz . xy) ≡ dimap bc yz . dimap ab xy" $ hedgehog $ do + + f <- forAllWith (const "f") genFun + ab <- forAllWith (const "ab") genFunction + bc <- forAllWith (const "bc") genFunction + xy <- forAllWith (const "xy") genFunction + yz <- forAllWith (const "xy") genFunction + + eqFun + (dimap (ab . bc) (yz . xy) f) + (dimap bc yz $ dimap ab xy f) + +eqFun :: Fun Maybe Int Int -> Fun Maybe Int Int -> PropertyT IO () +eqFun fun1 fun2 = do + x <- forAll genInt + unFun fun1 x === unFun fun2 x