diff --git a/LICENSE b/LICENSE new file mode 100644 --- /dev/null +++ b/LICENSE @@ -0,0 +1,202 @@ + + Apache License + Version 2.0, January 2004 + http://www.apache.org/licenses/ + + TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION + + 1. Definitions. + + "License" shall mean the terms and conditions for use, reproduction, + and distribution as defined by Sections 1 through 9 of this document. + + "Licensor" shall mean the copyright owner or entity authorized by + the copyright owner that is granting the License. + + "Legal Entity" shall mean the union of the acting entity and all + other entities that control, are controlled by, or are under common + control with that entity. For the purposes of this definition, + "control" means (i) the power, direct or indirect, to cause the + direction or management of such entity, whether by contract or + otherwise, or (ii) ownership of fifty percent (50%) or more of the + outstanding shares, or (iii) beneficial ownership of such entity. + + "You" (or "Your") shall mean an individual or Legal Entity + exercising permissions granted by this License. + + "Source" form shall mean the preferred form for making modifications, + including but not limited to software source code, documentation + source, and configuration files. + + "Object" form shall mean any form resulting from mechanical + transformation or translation of a Source form, including but + not limited to compiled object code, generated documentation, + and conversions to other media types. + + "Work" shall mean the work of authorship, whether in Source or + Object form, made available under the License, as indicated by a + copyright notice that is included in or attached to the work + (an example is provided in the Appendix below). + + "Derivative Works" shall mean any work, whether in Source or Object + form, that is based on (or derived from) the Work and for which the + editorial revisions, annotations, elaborations, or other modifications + represent, as a whole, an original work of authorship. For the purposes + of this License, Derivative Works shall not include works that remain + separable from, or merely link (or bind by name) to the interfaces of, + the Work and Derivative Works thereof. + + "Contribution" shall mean any work of authorship, including + the original version of the Work and any modifications or additions + to that Work or Derivative Works thereof, that is intentionally + submitted to Licensor for inclusion in the Work by the copyright owner + or by an individual or Legal Entity authorized to submit on behalf of + the copyright owner. For the purposes of this definition, "submitted" + means any form of electronic, verbal, or written communication sent + to the Licensor or its representatives, including but not limited to + communication on electronic mailing lists, source code control systems, + and issue tracking systems that are managed by, or on behalf of, the + Licensor for the purpose of discussing and improving the Work, but + excluding communication that is conspicuously marked or otherwise + designated in writing by the copyright owner as "Not a Contribution." + + "Contributor" shall mean Licensor and any individual or Legal Entity + on behalf of whom a Contribution has been received by Licensor and + subsequently incorporated within the Work. + + 2. Grant of Copyright License. Subject to the terms and conditions of + this License, each Contributor hereby grants to You a perpetual, + worldwide, non-exclusive, no-charge, royalty-free, irrevocable + copyright license to reproduce, prepare Derivative Works of, + publicly display, publicly perform, sublicense, and distribute the + Work and such Derivative Works in Source or Object form. + + 3. Grant of Patent License. Subject to the terms and conditions of + this License, each Contributor hereby grants to You a perpetual, + worldwide, non-exclusive, no-charge, royalty-free, irrevocable + (except as stated in this section) patent license to make, have made, + use, offer to sell, sell, import, and otherwise transfer the Work, + where such license applies only to those patent claims licensable + by such Contributor that are necessarily infringed by their + Contribution(s) alone or by combination of their Contribution(s) + with the Work to which such Contribution(s) was submitted. If You + institute patent litigation against any entity (including a + cross-claim or counterclaim in a lawsuit) alleging that the Work + or a Contribution incorporated within the Work constitutes direct + or contributory patent infringement, then any patent licenses + granted to You under this License for that Work shall terminate + as of the date such litigation is filed. + + 4. Redistribution. You may reproduce and distribute copies of the + Work or Derivative Works thereof in any medium, with or without + modifications, and in Source or Object form, provided that You + meet the following conditions: + + (a) You must give any other recipients of the Work or + Derivative Works a copy of this License; and + + (b) You must cause any modified files to carry prominent notices + stating that You changed the files; and + + (c) You must retain, in the Source form of any Derivative Works + that You distribute, all copyright, patent, trademark, and + attribution notices from the Source form of the Work, + excluding those notices that do not pertain to any part of + the Derivative Works; and + + (d) If the Work includes a "NOTICE" text file as part of its + distribution, then any Derivative Works that You distribute must + include a readable copy of the attribution notices contained + within such NOTICE file, excluding those notices that do not + pertain to any part of the Derivative Works, in at least one + of the following places: within a NOTICE text file distributed + as part of the Derivative Works; within the Source form or + documentation, if provided along with the Derivative Works; or, + within a display generated by the Derivative Works, if and + wherever such third-party notices normally appear. The contents + of the NOTICE file are for informational purposes only and + do not modify the License. You may add Your own attribution + notices within Derivative Works that You distribute, alongside + or as an addendum to the NOTICE text from the Work, provided + that such additional attribution notices cannot be construed + as modifying the License. + + You may add Your own copyright statement to Your modifications and + may provide additional or different license terms and conditions + for use, reproduction, or distribution of Your modifications, or + for any such Derivative Works as a whole, provided Your use, + reproduction, and distribution of the Work otherwise complies with + the conditions stated in this License. + + 5. Submission of Contributions. Unless You explicitly state otherwise, + any Contribution intentionally submitted for inclusion in the Work + by You to the Licensor shall be under the terms and conditions of + this License, without any additional terms or conditions. + Notwithstanding the above, nothing herein shall supersede or modify + the terms of any separate license agreement you may have executed + with Licensor regarding such Contributions. + + 6. Trademarks. This License does not grant permission to use the trade + names, trademarks, service marks, or product names of the Licensor, + except as required for reasonable and customary use in describing the + origin of the Work and reproducing the content of the NOTICE file. + + 7. Disclaimer of Warranty. Unless required by applicable law or + agreed to in writing, Licensor provides the Work (and each + Contributor provides its Contributions) on an "AS IS" BASIS, + WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or + implied, including, without limitation, any warranties or conditions + of TITLE, NON-INFRINGEMENT, MERCHANTABILITY, or FITNESS FOR A + PARTICULAR PURPOSE. You are solely responsible for determining the + appropriateness of using or redistributing the Work and assume any + risks associated with Your exercise of permissions under this License. + + 8. Limitation of Liability. In no event and under no legal theory, + whether in tort (including negligence), contract, or otherwise, + unless required by applicable law (such as deliberate and grossly + negligent acts) or agreed to in writing, shall any Contributor be + liable to You for damages, including any direct, indirect, special, + incidental, or consequential damages of any character arising as a + result of this License or out of the use or inability to use the + Work (including but not limited to damages for loss of goodwill, + work stoppage, computer failure or malfunction, or any and all + other commercial damages or losses), even if such Contributor + has been advised of the possibility of such damages. + + 9. Accepting Warranty or Additional Liability. While redistributing + the Work or Derivative Works thereof, You may choose to offer, + and charge a fee for, acceptance of support, warranty, indemnity, + or other liability obligations and/or rights consistent with this + License. However, in accepting such obligations, You may act only + on Your own behalf and on Your sole responsibility, not on behalf + of any other Contributor, and only if You agree to indemnify, + defend, and hold each Contributor harmless for any liability + incurred by, or claims asserted against, such Contributor by reason + of your accepting any such warranty or additional liability. + + END OF TERMS AND CONDITIONS + + APPENDIX: How to apply the Apache License to your work. + + To apply the Apache License to your work, attach the following + boilerplate notice, with the fields enclosed by brackets "[]" + replaced with your own identifying information. (Don't include + the brackets!) The text should be enclosed in the appropriate + comment syntax for the file format. We also recommend that a + file or class name and description of purpose be included on the + same "printed page" as the copyright notice for easier + identification within third-party archives. + + Copyright [yyyy] [name of copyright owner] + + Licensed under the Apache License, Version 2.0 (the "License"); + you may not use this file except in compliance with the License. + You may obtain a copy of the License at + + http://www.apache.org/licenses/LICENSE-2.0 + + Unless required by applicable law or agreed to in writing, software + distributed under the License is distributed on an "AS IS" BASIS, + WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + See the License for the specific language governing permissions and + limitations under the License. diff --git a/data-result.cabal b/data-result.cabal new file mode 100644 --- /dev/null +++ b/data-result.cabal @@ -0,0 +1,33 @@ +name: data-result +version: 1.0 +cabal-version: >=1.10 +build-type: Simple +license: Apache-2.0 +license-file: LICENSE +copyright: Copyright (C) 2016 Wojciech Danilo +maintainer: Wojciech Danilo +stability: experimental +homepage: https://github.com/wdanilo/data-result +bug-reports: https://github.com/wdanilo/data-result/issues +synopsis: Data types for returning results distinguishable by types. +category: Text +author: Wojciech Danilo + +library + exposed-modules: + Data.Result + build-depends: + base >=4.6 && <4.9, + poly-control -any, + prologue -any + default-language: Haskell2010 + default-extensions: ConstraintKinds DataKinds DefaultSignatures + DeriveDataTypeable DeriveFoldable DeriveFunctor DeriveGeneric + DeriveTraversable DoAndIfThenElse EmptyDataDecls FlexibleContexts + FlexibleInstances GeneralizedNewtypeDeriving InstanceSigs + LambdaCase MultiParamTypeClasses OverloadedStrings + StandaloneDeriving TemplateHaskell TupleSections TypeOperators + ViewPatterns TypeFamilies + hs-source-dirs: src + ghc-options: -Wall -O2 + diff --git a/src/Data/Result.hs b/src/Data/Result.hs new file mode 100644 --- /dev/null +++ b/src/Data/Result.hs @@ -0,0 +1,89 @@ +module Data.Result where + +import Prologue + +import Control.Monad.Poly +import Control.Applicative.Poly +import Data.Maybe (fromJust) + +----------------------------- +-- === Result wrappers === -- +----------------------------- + +data Ok a = Ok a deriving (Show, Functor, Foldable, Traversable) +data Error e a = Error deriving (Show) + + +-- Utils + +fromOk :: Ok a -> a +fromOk (Ok a) = a + +class MaybeResult m where maybeResult :: m a -> Maybe a +instance MaybeResult Ok where maybeResult = Just ∘ unwrap' +instance MaybeResult (Error e) where maybeResult = const Nothing + +unsafeFromResult :: MaybeResult m => m a -> a +unsafeFromResult = fromJust ∘ maybeResult + + +class IfOk m where ifOk :: m a -> (a -> b) -> b -> b +instance IfOk Ok where ifOk (Ok a) f _ = f a +instance IfOk (Error e) where ifOk _ _ e = e + +-- Basic instances + +instance Applicative Ok where pure = Ok + Ok f <*> Ok a = Ok $ f a + +instance Monad Ok where return = Ok + Ok a >>= f = f a + + +instance Functor (Error e) where fmap f e = Error +instance Applicative (Error e) where pure _ = Error + _ <*> _ = Error + +instance Monad (Error e) where return _ = Error + _ >>= f = Error + + +-- Wrappers +instance Coated Ok +type instance Unlayered (Ok a) = a +instance Layered (Ok a) +instance Rewrapped (Ok a) (Ok a') +instance Wrapped (Ok a) where + type Unwrapped (Ok a) = a + _Wrapped' = iso (\(Ok a) -> a) Ok + +-- Poly instances + +type instance PolyBind Ok Ok = Ok +type instance PolyBind (Error e) a = Error e +type instance PolyBind Ok (Error e) = Error e + +instance {-# OVERLAPPABLE #-} PolyApplicative (Error e) a where _ <<*>> _ = Error +instance {-# OVERLAPPABLE #-} PolyApplicative (Error e)(Error e) where _ <<*>> _ = Error +instance {-# OVERLAPPABLE #-} PolyApplicative Ok (Error e) where _ <<*>> _ = Error + +instance PolyMonad (Error e) a where _ >>>= _ = Error +instance PolyMonad Ok (Error e) where Ok a >>>= f = f a + + +------------------------------- +-- === Result constrains === -- +------------------------------- + +class CompilationError a + +class Check a (ok :: Bool) +instance Check a 'True +instance CompilationError a => Check a 'False + +type family Asserted e check where Asserted e 'True = Ok + Asserted e 'False = Error e + +class Assert e (ok :: Bool) where assert :: Proxy e -> Proxy ok -> a -> Asserted e ok a +instance Assert e 'True where assert _ _ = Ok +instance Assert e 'False where assert _ _ _ = Error