diff --git a/CHANGELOG.md b/CHANGELOG.md new file mode 100644 --- /dev/null +++ b/CHANGELOG.md @@ -0,0 +1,11 @@ +# Changelog + +`ghc-plugin-non-empty` uses [PVP Versioning][1]. +The changelog is available [on GitHub][2]. + +## 0.0.0.0 — July 17, 2022 🌇 + +* Initially created. + +[1]: https://pvp.haskell.org +[2]: https://github.com/chshersh/ghc-plugin-non-empty/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 +1,77 @@ +# ghc-plugin-non-empty + +[![GitHub CI](https://github.com/chshersh/ghc-plugin-non-empty/workflows/CI/badge.svg)](https://github.com/chshersh/ghc-plugin-non-empty/actions) +[![Hackage](https://img.shields.io/hackage/v/ghc-plugin-non-empty.svg?logo=haskell)](https://hackage.haskell.org/package/ghc-plugin-non-empty) +[![MPL-2.0 license](https://img.shields.io/badge/license-MPL--2.0-blue.svg)](LICENSE) + +GHC Compiler Plugin for automatically converting list literals to the +`NonEmpty` type from the `Data.List.NonEmpty` module in `base`. + +This plugin checks statically defined list literals and transforms +them into `NonEmpty` lists during compile time. In other words, it +provides compile-time guarantees for non-emptiness checks and allows +the following expression to type-check: + +```haskell +portsToListen :: NonEmpty Int +portsToListen = [8000, 8080, 8081] +``` + +Compare to usage without the plugin: + +```haskell +portsToListen :: NonEmpty Int +portsToListen = 8000 :| [8080, 8081] +``` + +> ℹ️ **DISCLAIMER:** `ghc-plugin-non-empty` is developed and +> maintained in free time by volunteers. The development may continue +> for decades or may stop tomorrow. You can use +> [GitHub Sponsorship](https://github.com/sponsors/chshersh) to support +> the development of this project. + +## How to use? + +`ghc-plugin-non-empty` is compatible with the following GHC +versions — [supported versions](https://matrix.hackage.haskell.org/#/package/ghc-plugin-non-empty) + +In order to start using `ghc-plugin-non-empty` in your project, you'll +need to set it up with these steps: + +1. Add the dependency on `ghc-plugin-non-empty` in your project's + `.cabal` file. For this, you should modify the `build-depends` + section according to the below section: + + ```haskell + build-depends: + , base ^>= LATEST_SUPPORTED_BASE + , ghc-plugin-non-empty ^>= LATEST_VERSION + ``` + +2. To use this package, refer to the below example. + + ```haskell + {-# OPTIONS_GHC -fplugin=GhcPluginNonEmpty #-} + + module Main (main) where + + import Data.List.NonEmpty (NonEmpty) + + exampleList :: NonEmpty Int + exampleList = [100, 5, 74] + + main :: IO () + main = print exampleList + ``` + +## For contributors + +Check [CONTRIBUTING.md](https://github.com/chshersh/ghc-plugin-non-empty/blob/main/CONTRIBUTING.md) +for contributing guidelines. + +To build the project and run the tests, use `cabal`: + +```shell +cabal build all +cabal test --enable-tests --test-show-details=direct +``` diff --git a/ghc-plugin-non-empty.cabal b/ghc-plugin-non-empty.cabal new file mode 100644 --- /dev/null +++ b/ghc-plugin-non-empty.cabal @@ -0,0 +1,104 @@ +cabal-version: 3.0 +name: ghc-plugin-non-empty +version: 0.0.0.0 +synopsis: GHC Plugin for non-empty lists +description: + GHC Plugin for compile-time transformation of list literals to @NonEmpty@ lists. + + @ + {-# __OPTIONS_GHC__ -fplugin=GhcPluginNonEmpty #-} + + __import__ Data.List.NonEmpty (NonEmpty) + + portsToListen :: NonEmpty Int + portsToListen = [8000, 8080, 8081] + @ + + See [README.md](https://github.com/chshersh/ghc-plugin-non-empty#ghc-plugin-non-empty) + for more details. +homepage: https://github.com/chshersh/ghc-plugin-non-empty +bug-reports: https://github.com/chshersh/ghc-plugin-non-empty/issues +license: MPL-2.0 +license-file: LICENSE +author: Dmitrii Kovanikov +maintainer: Dmitrii Kovanikov +copyright: 2022 Dmitrii Kovanikov +category: GHC, Compiler Plugin +build-type: Simple +extra-doc-files: README.md + CHANGELOG.md +tested-with: GHC == 9.2.3 + +source-repository head + type: git + location: https://github.com/chshersh/ghc-plugin-non-empty.git + +common common-options + build-depends: base ^>= 4.16 + + ghc-options: -Wall + -Wcompat + -Widentities + -Wincomplete-uni-patterns + -Wincomplete-record-updates + -Wredundant-constraints + -Wnoncanonical-monad-instances + 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 + if impl(ghc >= 9.0) + ghc-options: -Winvalid-haddock + if impl(ghc >= 9.2) + ghc-options: -Wredundant-bang-patterns + -Woperator-whitespace + + default-language: Haskell2010 + default-extensions: ConstraintKinds + DeriveGeneric + DerivingStrategies + GeneralizedNewtypeDeriving + InstanceSigs + KindSignatures + LambdaCase + OverloadedStrings + RecordWildCards + ScopedTypeVariables + StandaloneDeriving + TupleSections + TypeApplications + ViewPatterns + +library + import: common-options + hs-source-dirs: src + exposed-modules: GhcPluginNonEmpty + + build-depends: + , ghc ^>= 9.2 + , syb ^>= 0.7 + +test-suite ghc-plugin-non-empty-test + import: common-options + type: exitcode-stdio-1.0 + hs-source-dirs: test + + main-is: Spec.hs + other-modules: Test.Data.Fail + Test.Data.Plain + Test.Data.Overloaded + + build-depends: + , ghc-plugin-non-empty + , hspec ^>= 2.10 + + ghc-options: -threaded + -rtsopts + -with-rtsopts=-N diff --git a/src/GhcPluginNonEmpty.hs b/src/GhcPluginNonEmpty.hs new file mode 100644 --- /dev/null +++ b/src/GhcPluginNonEmpty.hs @@ -0,0 +1,304 @@ +{-# LANGUAGE DeriveDataTypeable #-} + +{- | +Module : Iris +Copyright : (c) 2022 Dmitrii Kovanikov +SPDX-License-Identifier : MPL-2.0 +Maintainer : Dmitrii Kovanikov +Stability : Stable +Portability : Portable + +GHC Plugin for rewriting list literals of non-empty list to 'NonEmpty' +type. Enable the plugin in a module where you want to use it like on +the example below: + +@ +\{\-\# __OPTIONS_GHC__ -fplugin=GhcPluginNonEmpty \#\-\} + +__import__ "Data.List.NonEmpty" ('NonEmpty') + +portsToListen :: 'NonEmpty' 'Int' +portsToListen = [8000, 8080, 8081] +@ + +You can also enable the plugin globally in your entire project from +the @.cabal@ file: + +@ +library + ... + ghc-options: -fplugin=GhcPluginNonEmpty +@ + +It guarantees that only non-empty lists will be automatically +rewritten. Otherwise, if you use an empty list: + +@ +portsToListen :: 'NonEmpty' 'Int' +portsToListen = [] +@ + +You'll see ordinary compiler error: + +@ +src\/Path\/To\/My\/Module:34:17: error: + • Couldn't match expected type: NonEmpty Int + with actual type: [a0] + • In the expression: [] + In an equation for ‘portsToListen’: portsToListen = [] + | +34 | portsToListen = [] + | ^^ +@ + +@since 0.0.0.0 +-} + +module GhcPluginNonEmpty + ( plugin + + -- * Internal typeclass for the plugin work + , GhcPlugnNonEmptyClass (..) + , cons + ) where + +import GHC.Driver.Plugins (CommandLineOption, Plugin (..), defaultPlugin, purePlugin) +import GHC.Hs.Expr (HsWrap (..), XXExprGhcTc (WrapExpr)) +import GHC.Hs.Extension (GhcRn, GhcTc) +import GHC.Iface.Env (lookupOrig) +import GHC.Parser.Annotation (EpAnn (..), SrcSpanAnn' (..)) +import GHC.Plugins (Name, mkVarOcc) +import GHC.Tc.Types (TcGblEnv (tcg_binds), TcM) +import GHC.Tc.Types.Evidence (HsWrapper, pprHsWrapper) +import GHC.Tc.Utils.Monad (getTopEnv) +import GHC.Types.SrcLoc (GenLocated (L), SrcSpan (..), UnhelpfulSpanReason (..)) +import GHC.Types.TyThing (MonadThings (lookupId)) +import GHC.Types.Var (Id) +import GHC.Unit.Finder (FindResult (..), findImportedModule) +import GHC.Unit.Module.ModSummary (ModSummary) +import GHC.Utils.Outputable (defaultSDocContext, renderWithContext, sdocPrintTypecheckerElaboration, + text) +import Language.Haskell.Syntax.Decls (HsGroup) +import Language.Haskell.Syntax.Expr (HsExpr (..), LHsExpr) +import Language.Haskell.Syntax.Extension (NoExtField (..)) + +import Control.Monad.IO.Class (MonadIO (..)) +import Data.Generics.Aliases (mkM, mkT) +import Data.Generics.Schemes (everywhere, everywhereM) +import Data.List (isInfixOf) +import Data.List.NonEmpty (NonEmpty (..)) + +import qualified GHC + + + +{- | Main compiler plugin. Use the following GHC option to enable it: + +@ +\{\-\# OPTIONS_GHC -fplugin=GhcPluginNonEmpty \#\-\} +@ + +Implemented in two steps: + +1. Rewrites @[3, 1, 2]@ to @'_xxx_ghc_plugin_nonEmpty_fromList' 'cons' [3, 1, 2]@ +2. Find applications of '_xxx_ghc_plugin_nonEmpty_fromList' and rewrites them to + @'cons' 3 [1, 2]@ + +@since 0.0.0.0 +-} +plugin :: Plugin +plugin = defaultPlugin + { pluginRecompile = purePlugin + + -- 1. Identify list constructors and make them uniform + , renamedResultAction = wrapLists + + -- 2. Replace list literals with NonEmpty list constructors + , typeCheckResultAction = replaceNonEmpty + } + +wrapLists + :: [CommandLineOption] + -> TcGblEnv + -> HsGroup GhcRn + -> TcM (TcGblEnv, HsGroup GhcRn) +wrapLists _options tcGblEnv hsGroup = do + hscEnv <- getTopEnv + + Found _ ghcPluginNonEmptyModule <- liftIO $ findImportedModule + hscEnv + (GHC.mkModuleName "GhcPluginNonEmpty") + Nothing + + ghcPluginNonEmptyFromListName <- lookupOrig + ghcPluginNonEmptyModule + (mkVarOcc "_xxx_ghc_plugin_nonEmpty_fromList") + + nonEmptyCtor <- lookupOrig + ghcPluginNonEmptyModule + (mkVarOcc "cons") + + let newHsGroup = everywhere + (mkT $ rewriteListLiterals ghcPluginNonEmptyFromListName nonEmptyCtor) + hsGroup + + pure (tcGblEnv, newHsGroup) + +rewriteListLiterals + :: Name + -> Name + -> LHsExpr GhcRn + -> LHsExpr GhcRn +rewriteListLiterals ghcPluginNonEmptyFromListName nonEmptyCtor = \case + -- rewrite only explicit list literals + l@(L _ ExplicitList{}) -> + -- this becomes: + -- _xxx_ghc_plugin_nonEmpty_fromList cons [3, 1, 2] + app (app (var ghcPluginNonEmptyFromListName) (var nonEmptyCtor)) l + + -- don't touch other expresions + expr -> + expr + +mkSpan :: a -> GenLocated (SrcSpanAnn' (EpAnn ann)) a +mkSpan = L $ SrcSpanAnn EpAnnNotUsed $ UnhelpfulSpan UnhelpfulGenerated + +app :: LHsExpr GhcRn -> LHsExpr GhcRn -> LHsExpr GhcRn +app l r = mkSpan $ HsApp EpAnnNotUsed l r + +var :: Name -> LHsExpr GhcRn +var name = mkSpan $ HsVar NoExtField $ mkSpan name + +replaceNonEmpty + :: [CommandLineOption] + -> ModSummary + -> TcGblEnv + -> TcM TcGblEnv +replaceNonEmpty _options _modSummary tcGblEnv = do + hscEnv <- getTopEnv + + Found _ ghcPluginNonEmptyModule <- liftIO $ findImportedModule + hscEnv + (GHC.mkModuleName "GhcPluginNonEmpty") + Nothing + + ghcPluginNonEmptyFromListName <- lookupOrig + ghcPluginNonEmptyModule + (mkVarOcc "_xxx_ghc_plugin_nonEmpty_fromList") + + ghcPluginNonEmptyFromListId <- lookupId ghcPluginNonEmptyFromListName + + newTcgBinds <- everywhereM + (mkM $ rewriteToNonEmpty ghcPluginNonEmptyFromListId) + (tcg_binds tcGblEnv) + + pure tcGblEnv{ tcg_binds = newTcgBinds } + +rewriteToNonEmpty + :: Id + -> LHsExpr GhcTc + -> TcM (LHsExpr GhcTc) +rewriteToNonEmpty ghcPluginNonEmptyFromListId = \case + L + _ + (HsApp + _ + (L + _ + (HsApp + _ + (L + _ + (XExpr + (WrapExpr + (HsWrap + varType + (HsVar _ (L _ varName)) + ) + ) + ) + ) + nonEmptyCtor + ) + ) + r@(L + _ + (ExplicitList listType items) + ) + ) + | varName == ghcPluginNonEmptyFromListId -> + if isNonEmptyWrapper varType + -- transform non-empty lists + then case items of + -- if the list is empty, we just remove our wrapper and let GHC deal with it + [] -> pure r + + -- otherwise, we use ctor to create NonEmpty + x : xs -> pure $ mkSpan $ HsApp EpAnnNotUsed + (mkSpan $ HsApp EpAnnNotUsed nonEmptyCtor x) + (mkSpan $ ExplicitList listType xs) + + -- remove the wrapper for ordinary lists + else pure r + + expr -> pure expr + +{- | This function uses a dirty hack to check if the inferred type for +'__xxx_ghc_plugin_nonEmpty_fromList' is for 'NonEmpty'. +-} +isNonEmptyWrapper :: HsWrapper -> Bool +isNonEmptyWrapper hsWrapper = "@NonEmpty" `isInfixOf` strWrapper + where + -- HsWrapper pretty-printed as 'String' + strWrapper :: String + strWrapper = renderWithContext + defaultSDocContext { sdocPrintTypecheckerElaboration = True } + $ pprHsWrapper hsWrapper (\_ -> text "wtf?") + +-------------------------- +-- List wrapper +-------------------------- + +{- | ⚠️ __WARNING! Don't use this typeclass!__ ⚠️ + +This is an internal typeclass for the plugin to work correctly but it +must be imported from this module. Don't use methods of this typeclass +in your code as it may result in incorrect compilation of your code. + +@since 0.0.0.0 +-} +class GhcPlugnNonEmptyClass listOf where + -- | @since 0.0.0.0 + _xxx_ghc_plugin_nonEmpty_fromList + :: (a -> [a] -> NonEmpty a) + -- ^ Typechecked non-empty constructor + -> [a] + -- ^ List literal we're going to rewrite + -> listOf a + -- ^ Resulting list + +-- | @since 0.0.0.0 +instance GhcPlugnNonEmptyClass [] where + _xxx_ghc_plugin_nonEmpty_fromList :: (a -> [a] -> NonEmpty a) -> [a] -> [a] + _xxx_ghc_plugin_nonEmpty_fromList _ l = l + {-# INLINE _xxx_ghc_plugin_nonEmpty_fromList #-} + +-- | @since 0.0.0.0 +instance GhcPlugnNonEmptyClass NonEmpty where + _xxx_ghc_plugin_nonEmpty_fromList :: (a -> [a] -> NonEmpty a) -> [a] -> NonEmpty a + _xxx_ghc_plugin_nonEmpty_fromList = error $ unlines + [ "Panic! At The 'ghc-plugin-non-empty'" + , " Remained usage of: _xxx_ghc_plugin_nonEmpty_fromList :: [a] -> NonEmpty a" + , "" + , "If you see this error, please open an issue in the plugin with your code example:" + , "" + , " * https://github.com/chshersh/ghc-plugin-non-empty/issues/new" + ] + {-# NOINLINE _xxx_ghc_plugin_nonEmpty_fromList #-} + +{- | Constructor for 'NonEmpty'. Named alias to ':|'. + +@since 0.0.0.0 +-} +cons :: a -> [a] -> NonEmpty a +cons = (:|) diff --git a/test/Spec.hs b/test/Spec.hs new file mode 100644 --- /dev/null +++ b/test/Spec.hs @@ -0,0 +1,44 @@ +{-# LANGUAGE BangPatterns #-} + +module Main (main) where + +import Control.Exception (ErrorCall, TypeError) +import Data.List.NonEmpty (NonEmpty (..)) +import Test.Hspec (describe, hspec, it, shouldBe, shouldThrow) + +import Test.Data.Fail as Test +import Test.Data.Overloaded as Test +import Test.Data.Plain as Test + + +main :: IO () +main = hspec $ describe "GhcPluginNonEmpty.plugin" $ do + describe "Plain" $ do + it "doesn't change ordinary empty list" $ + Test.emptyList `shouldBe` [] + it "doesn't change ordinary non-empty list" $ + Test.listInt `shouldBe` [3, 1, 2] + it "correctly converts to non-empty int list" $ + Test.nonEmptyListInt `shouldBe` 5 :| [10, 7] + it "correctly converts to non-empty bool list" $ + Test.nonEmptyListBool `shouldBe` True :| [False] + it "correctly converts singleton non-empty int list" $ + Test.nonEmptyListSingleton `shouldBe` 42 :| [] + it "doesn't change explicit non-empty lists" $ + Test.nonEmptyListExplicit `shouldBe` 42 :| [50, 100] + + describe "Fail" $ + it "compiler error on trying to convert empty list to non-empty" $ do + let action = let !x = Test.emptyNonEmpty in pure x + action `shouldThrow` \(_ :: TypeError) -> True + + describe "Overloaded" $ do + it "doesn't change overloaded ordinary empty list" $ + Test.overloadedListEmpty `shouldBe` [] + it "doesn't change overloaded ordinary non-empty list" $ + Test.overloadedListInt `shouldBe` [3, 1, 2] + it "converts overloaded NonEmpty list" $ + Test.overloadedNonEmptyInt `shouldBe` 15 :| [6, 7] + it "runtime error on trying to convert empty list to non-empty" $ do + let action = let !x = Test.overloadedEmptyNonEmpty in pure x + action `shouldThrow` \(_ :: ErrorCall) -> True diff --git a/test/Test/Data/Fail.hs b/test/Test/Data/Fail.hs new file mode 100644 --- /dev/null +++ b/test/Test/Data/Fail.hs @@ -0,0 +1,13 @@ +{-# OPTIONS_GHC -fplugin=GhcPluginNonEmpty #-} +{-# OPTIONS_GHC -fdefer-type-errors #-} +{-# OPTIONS_GHC -Wno-deferred-type-errors #-} + +module Test.Data.Fail + ( emptyNonEmpty + ) where + +import Data.List.NonEmpty (NonEmpty) + + +emptyNonEmpty :: NonEmpty Int +emptyNonEmpty = [] diff --git a/test/Test/Data/Overloaded.hs b/test/Test/Data/Overloaded.hs new file mode 100644 --- /dev/null +++ b/test/Test/Data/Overloaded.hs @@ -0,0 +1,24 @@ +{-# OPTIONS_GHC -fplugin=GhcPluginNonEmpty #-} + +{-# LANGUAGE OverloadedLists #-} + +module Test.Data.Overloaded + ( overloadedListEmpty + , overloadedListInt + , overloadedNonEmptyInt + , overloadedEmptyNonEmpty + ) where + +import Data.List.NonEmpty (NonEmpty) + +overloadedListEmpty :: [Int] +overloadedListEmpty = [] + +overloadedListInt :: [Int] +overloadedListInt = [3, 1, 2] + +overloadedNonEmptyInt :: NonEmpty Int +overloadedNonEmptyInt = [15, 6, 7] + +overloadedEmptyNonEmpty :: NonEmpty Int +overloadedEmptyNonEmpty = [] diff --git a/test/Test/Data/Plain.hs b/test/Test/Data/Plain.hs new file mode 100644 --- /dev/null +++ b/test/Test/Data/Plain.hs @@ -0,0 +1,31 @@ +{-# OPTIONS_GHC -fplugin=GhcPluginNonEmpty #-} + +module Test.Data.Plain + ( emptyList + , listInt + , nonEmptyListInt + , nonEmptyListBool + , nonEmptyListSingleton + , nonEmptyListExplicit + ) where + +import Data.List.NonEmpty (NonEmpty (..)) + + +emptyList :: [Int] +emptyList = [] + +listInt :: [Int] +listInt = [3, 1, 2] + +nonEmptyListInt :: NonEmpty Int +nonEmptyListInt = [5, 10, 7] + +nonEmptyListBool :: NonEmpty Bool +nonEmptyListBool = [True, False] + +nonEmptyListSingleton :: NonEmpty Int +nonEmptyListSingleton = [42] + +nonEmptyListExplicit :: NonEmpty Int +nonEmptyListExplicit = 42 :| [50, 100]