diff --git a/LICENSE b/LICENSE new file mode 100644 --- /dev/null +++ b/LICENSE @@ -0,0 +1,201 @@ + 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/README.md b/README.md new file mode 100644 --- /dev/null +++ b/README.md @@ -0,0 +1,209 @@ +# par-dual + +[![CI Status](https://github.com/gvolpe/par-dual/workflows/Haskell%20CI/badge.svg)](https://github.com/gvolpe/par-dual/actions) + +The [PureScript](https://www.purescript.org/) language defines a [Parallel](https://pursuit.purescript.org/packages/purescript-parallel/4.0.0/docs/Control.Parallel.Class#t:Parallel) typeclass in the `parallel` package. Quoting its documentation: + +> The `Parallel` class abstracts over monads which support parallel composition via some related `Applicative`. + +The same typeclass is defined in the [Scala](https://www.scala-lang.org/) language, as part of the [Cats](https://typelevel.org/cats/typeclasses/parallel.html) library. + +This typeclass has been controversial, in a sense, for not having strong laws. However, it has been proven to be actually useful in real-world applications. + +The idea of this package is to bring this power over to the Haskell language while exploring the design space to identify and define stronger laws (if possible). + +Originally, this idea has been described in [this blogpost](https://gvolpe.github.io/blog/parallel-typeclass-for-haskell/). + +## ParDual + +Here's the definition of the same typeclass in Haskell: + +```haskell +class (Monad m, Applicative f) => ParDual f m | m -> f, f -> m where + parallel :: forall a . m a -> f a + sequential :: forall a . f a -> m a +``` + +I decided to call it `ParDual` instead of `Parallel`, because this *duality* doesn't always define a `sequential` and `parallel` relationship. Such is the case between `[]` and `ZipList`, as we will soon discover. + +It defines two functions, which are natural transformations between a `Monad m` and an `Applicative f`. It could also be seen as a typeclass version of an isomorphism such as `forall a . Iso (f a) (m a)`. + +The most common and useful relationships are both `Either` / `Validation` and `IO` / `Concurrently`. + +```haskell +instance Semigroup e => ParDual (Validation e) (Either e) where + parallel = fromEither + sequential = toEither + +instance ParDual Concurrently IO where + parallel = Concurrently + sequential = runConcurrently +``` + +`Validation` comes from the [validators](https://hackage.haskell.org/package/validators) package, whereas `Concurrently` comes from the [async](https://hackage.haskell.org/package/async) package. + +Additionally, we can define a lot of powerful functions solely in terms of `Applicative`, `Monad`, and `ParDual`. A few other functions might require extra requirements, such as `Traversable`. + +### parMapN + +The `parMapN` set of functions are analogue to combining `<$>` and `<*>`, for any dual `Applicative`. + +```haskell +parMap2 + :: (Applicative f, Monad m, ParDual f m) + => m a0 + -> m a1 + -> (a0 -> a1 -> a) + -> m a +``` + +In this case, `parMap2` takes only two computations and a function, but you can find other versions up to `parMap6`. If there is demand, we can consider abstracting over its arity, in order to compose an arbitrary number of computations. + +For example, if we define a `Person` datatype with two fields: + +```haskell +type Name = Refined NonEmpty String +type Age = Refined (GreaterThan 17) Int + +data Person = Person + { personAge :: Age + , personName :: Name + } deriving Show +``` + +We can then validate different inputs, while accumulating errors on the left side, even when our type is `Either [String] Person`. + +```haskell +mkPerson :: Int -> String -> Either [String] Person +mkPerson a n = parMap2 (ref a) (ref n) Person +``` + +Where `ref` is a generic function that converts `RefineException`s to `[String]`: + +```haskell +ref :: Predicate p x => x -> Either [String] (Refined p x) +ref x = left (\e -> [show e]) (refine x) +``` + +In case of two invalid inputs, we will get as a result a list of validation errors: + +```haskell +mkPerson 10 "" == Left ["error 1", "error 2"] +``` + +If `parMapN` didn't exist, we could do the same by manually converting between `Either` and `Validation` (which is exactly what `parMapN` does via the `ParDual` class). + +```haskell +mkPerson :: Int -> String -> Either [String] Person +mkPerson a n = toEither $ Person <$> fromEither (ref a) <*> fromEither (ref n) +``` + +Though, we can see how cumbersome and boilerplatey it gets. + +### parTraverse + +Another great application of the `ParDual` class is the definition of a `traverse` function that takes a `Monad` and a `Traversable t`, but that operates over its dual `Applicative`, and at the end it converts back to this `Monad`. + +```haskell +parTraverse + :: (Traversable t, Applicative f, Monad m, ParDual f m) + => (a -> m b) + -> t a + -> m (t b) +``` + +The type signature is exactly the same as `traverse`, except the constraints are different. + +We can appreciate its usability by looking at some examples. Here's one with `Either`: + +```haskell +f :: Int -> Either [String] Int +f n = Left [show n] + +traverse f [1..5] == Left ["1"] +parTraverse f [1..5] == Left ["1","2","3","4","5"] +``` + +Below there is another one with `IO`: + +```haskell +randomDelay :: IO () +randomDelay = do + r <- randomRIO (1, 10) + threadDelay (r * 500000) + +traverseIO :: IO () +traverseIO = traverse_ (\n -> randomDelay >> print n) [1 .. 10] + +parTraverseIO :: IO () +parTraverseIO = parTraverse_ (\n -> randomDelay >> print n) [1 .. 10] +``` + +The `traverse` version prints out numbers from 1 to 10 in sequence, while waiting for every random delay. So the output is pretty much `1 2 3 4 5 6 7 8 9 10`. + +The `parTraverse` version has a non-deterministic output, since it goes through `Concurrently` (`IO`'s dual). It is exactly what you would expect while using [mapConcurrently](https://hackage.haskell.org/package/async-2.2.2/docs/Control-Concurrent-Async.html#v:mapConcurrently). One possible output is `5 10 6 1 3 2 9 4 7 8`. + +### ZipList + +The dual `Applicative` instance of `[]` is the one defined by `ZipList`, which doesn't have anything to do with parallelism. + +```haskell +instance ParDual ZipList [] where + parallel = ZipList + sequential = getZipList +``` + +Let's have a look at the examples shown below. + +```haskell +((+) <$> [1..5] <*> [6..10]) == [7,8,9,10,11,8,9,10,11,12,9,10,11,12,13,10,11,12,13,14,11,12,13,14,15] + +parMap2 [1..5] [6..10] (+) == [7,9,11,13,15] +``` + +The standard version iterates over both lists "sequentially". That is, it iterates over the first one, and then over the second one, returning the cartesian product of both lists. + +Conversely, `ZipList`s only return the sum of the current elements of both lists such as `1 + 6`, `2 + 7`, and so on. It iterates over both lists in "parallel", effectively traversing both at once. + +### parBitraverse + +Operates over any `Bitraversable` such as `Either` or `(,,)`. + +```haskell +res1 = [("ba",'2','T'),("ba",'2','r'),("ba",'2','u'),("ba",'2','e'),("ba",'4','T'),("ba",'4','r'),("ba",'4','u'),("ba",'4','e')] + +(bitraverse show show ("ba", 24, True)) == res1 +``` + +The standard `bitraverse` for `(String, Int, Bool)` traverses over the second value and then over the third value, combining the results on each iteration. + +```haskell +(parBitraverse show show ("ba", 24, True)) == [("ba",'2','T'),("ba",'4','r')] +``` + +The dual variant traverses all the values at the same time, terminating as soon as either value is empty. + +## Test suite + +The test suite property-checks the functions defined in `ParDual` applied to different types of values. + +``` +$ nix-shell --run 'cabal new-run par-dual-tests' +━━━ Main ━━━ + ✓ prop_parMap2_on_success passed 100 tests. + ✓ prop_parMap2_accumulates_errors passed 100 tests. + ✓ prop_parTraverse_accumulates_errors passed 100 tests. + ✓ prop_parTraverse_io_is_concurrent passed 10 tests. + ✓ prop_parMap2_on_lists passed 100 tests. + ✓ prop_parBitraverse passed 100 tests. + ✓ 6 succeeded. +``` + +## Publishing + +Generating documentation and tarball file to upload. + +``` +$ cabal new-haddock --haddock-for-hackage --enable-doc +$ cabal upload -d dist-newstyle/par-dual-0.1.0.0-docs.tar.gz +$ cabal new-sdist diff --git a/Setup.hs b/Setup.hs new file mode 100644 --- /dev/null +++ b/Setup.hs @@ -0,0 +1,2 @@ +import Distribution.Simple +main = defaultMain diff --git a/par-dual.cabal b/par-dual.cabal new file mode 100644 --- /dev/null +++ b/par-dual.cabal @@ -0,0 +1,38 @@ +cabal-version: 2.4 + +name: par-dual +version: 0.1.0.0 +synopsis: ParDual class for Parallel <-> Sequential +description: Defines a ParDual class for a Parallel <-> Sequential relationship +homepage: https://github.com/gvolpe/par-dual +bug-reports: https://github.com/gvolpe/par-dual/issues +license: Apache-2.0 +license-file: LICENSE +category: Library +author: Gabriel Volpe +copyright: 2020 - Gabriel Volpe +maintainer: volpegabriel@gmail.com +build-type: Simple +extra-source-files: README.md + +library + exposed-modules: Control.ParDual.Class + build-depends: base >= 4.13.0 && < 4.14 + , async >= 2.2.2 && < 2.3 + , validators >= 0.0.1 && < 0.1 + hs-source-dirs: src + default-language: Haskell2010 + ghc-options: -Wall + +test-Suite par-dual-tests + type: exitcode-stdio-1.0 + main-is: Main.hs + hs-source-dirs: test + build-depends: base + , hedgehog + , par-dual + , refined + , template-haskell + , validators + default-language: Haskell2010 + ghc-options: -Wall -threaded -with-rtsopts -N diff --git a/src/Control/ParDual/Class.hs b/src/Control/ParDual/Class.hs new file mode 100644 --- /dev/null +++ b/src/Control/ParDual/Class.hs @@ -0,0 +1,178 @@ +{-# LANGUAGE FunctionalDependencies, RankNTypes, TypeOperators #-} + +{-| +Module : Control.ParDual.Class +Description : Definition of the 'ParDual' class and its functions. +Copyright : (c) Gabriel Volpe, 2020 +License : Apache-2.0 +Maintainer : volpegabriel@gmail.com +Stability : experimental + +You can find here functions such as 'parMap2', 'parTraverse', 'parBitraverse', etc. +-} +module Control.ParDual.Class where + +import Control.Applicative ( ZipList(..) ) +import Control.Concurrent.Async ( Concurrently(..) ) +import Data.Bitraversable ( Bitraversable + , bitraverse + ) +import Data.Functor ( void ) +import Data.Validation ( Validation + , toEither + , fromEither + ) + +{- | The ParDual class abstracts over 'Monad's that have a dual +'Applicative' instance that acts in a different useful way. + +E.g., the duality between 'Either' and 'Validation'. As well +as the duality between 'IO' and 'Concurrently'. + +It can also be seen as an isomorphism defined at the class level. +-} +class (Monad m, Applicative f) => ParDual f m | m -> f, f -> m where + {- | A natural transformation from 'm' to 'f' + -} + parallel :: forall a . m a -> f a + + {- | A natural transformation from 'f' to 'm' + -} + sequential :: forall a . f a -> m a + + {- | + It is the analogue to using '<$>' and '<*>' for the dual + 'Applicative' of the current 'Monad', as defined by the + relationship defined by the 'ParDual' instance. + -} + parMap2 :: m a0 -> m a1 -> (a0 -> a1 -> a) -> m a + parMap2 ma0 ma1 f = sequential $ f + <$> parallel ma0 + <*> parallel ma1 + + {- | + It is the analogue to using '<$>' and '<*>' for the dual + 'Applicative' of the current 'Monad', as defined by the + relationship defined by the 'ParDual' instance. + -} + parMap3 :: m a0 -> m a1 -> m a2 -> (a0 -> a1 -> a2 -> a) -> m a + parMap3 ma0 ma1 ma2 f = sequential $ f + <$> parallel ma0 + <*> parallel ma1 + <*> parallel ma2 + + {- | + It is the analogue to using '<$>' and '<*>' for the dual + 'Applicative' of the current 'Monad', as defined by the + relationship defined by the 'ParDual' instance. + -} + parMap4 :: m a0 -> m a1 -> m a2 -> m a3 -> (a0 -> a1 -> a2 -> a3 -> a) -> m a + parMap4 ma0 ma1 ma2 ma3 f = sequential $ f + <$> parallel ma0 + <*> parallel ma1 + <*> parallel ma2 + <*> parallel ma3 + + {- | + It is the analogue to using '<$>' and '<*>' for the dual + 'Applicative' of the current 'Monad', as defined by the + relationship defined by the 'ParDual' instance. + -} + parMap5 :: m a0 -> m a1 -> m a2 -> m a3 -> m a4 -> (a0 -> a1 -> a2 -> a3 -> a4 -> a) -> m a + parMap5 ma0 ma1 ma2 ma3 ma4 f = sequential $ f + <$> parallel ma0 + <*> parallel ma1 + <*> parallel ma2 + <*> parallel ma3 + <*> parallel ma4 + + {- | + It is the analogue to using '<$>' and '<*>' for the dual + 'Applicative' of the current 'Monad', as defined by the + relationship defined by the 'ParDual' instance. + -} + parMap6 :: m a0 -> m a1 -> m a2 -> m a3 -> m a4 -> m a5 -> (a0 -> a1 -> a2 -> a3 -> a4 -> a5 -> a) -> m a + parMap6 ma0 ma1 ma2 ma3 ma4 ma5 f = sequential $ f + <$> parallel ma0 + <*> parallel ma1 + <*> parallel ma2 + <*> parallel ma3 + <*> parallel ma4 + <*> parallel ma5 + + {- | + Same as 'traverse', except it uses the dual 'Applicative' of + the current 'Monad', as defined by the 'ParDual' relationship. + -} + parTraverse :: Traversable t => (a -> m b) -> t a -> m (t b) + parTraverse f ta = + let g a = parallel (f a) + res = sequenceA $ fmap g ta + in sequential res + + {- | + Same as 'Data.Foldable.traverse_', except it uses the dual 'Applicative' of + the current 'Monad', as defined by the 'ParDual' relationship. + -} + parTraverse_ :: Traversable t => (a -> m b) -> t a -> m () + parTraverse_ f = void . parTraverse f + + {- | + Same as 'sequence', except it uses the dual 'Applicative' of + the current 'Monad', as defined by the 'ParDual' relationship. + -} + parSequence :: Traversable t => t (m a) -> m (t a) + parSequence = parTraverse id + + {- | + Same as 'sequence_', except it uses the dual 'Applicative' of + the current 'Monad', as defined by the 'ParDual' relationship. + -} + parSequence_ :: Traversable t => t (m a) -> m () + parSequence_ = void . parSequence + + {- | + Same as '*>', except it uses the dual 'Applicative' of + the current 'Monad', as defined by the 'ParDual' relationship. + -} + parProductR :: m a -> m b -> m b + parProductR ma mb = parMap2 ma mb (\_ b -> b) + + {- | + Same as '<*', except it uses the dual 'Applicative' of + the current 'Monad', as defined by the 'ParDual' relationship. + -} + parProductL :: m a -> m b -> m a + parProductL ma mb = parMap2 ma mb const + + {- | + Same as 'bitraverse', except it uses the dual 'Applicative' of + the current 'Monad', as defined by the 'ParDual' relationship. + -} + parBitraverse :: Bitraversable t => (a -> m c) -> (b -> m d) -> t a b -> m (t c d) + parBitraverse ma mb tab = + let fa = (\a -> parallel (ma a)) + fb = (\b -> parallel (mb b)) + res = bitraverse fa fb tab + in sequential res + + {- | + Same as 'Data.Traversable.bisequence', except it uses the dual 'Applicative' of + the current 'Monad', as defined by the 'ParDual' relationship. + -} + parBisequence :: Bitraversable t => t (m a) (m b) -> m (t a b) + parBisequence = parBitraverse id id + +--------------------- Instances ---------------------------- + +instance Semigroup e => ParDual (Validation e) (Either e) where + parallel = fromEither + sequential = toEither + +instance ParDual Concurrently IO where + parallel = Concurrently + sequential = runConcurrently + +instance ParDual ZipList [] where + parallel = ZipList + sequential = getZipList diff --git a/test/Main.hs b/test/Main.hs new file mode 100644 --- /dev/null +++ b/test/Main.hs @@ -0,0 +1,132 @@ +{-# LANGUAGE DataKinds, OverloadedStrings, TemplateHaskell #-} + +module Main where + +import Control.Arrow ( left ) +import Control.Concurrent ( threadDelay ) +import Control.ParDual.Class +import Control.Monad ( unless ) +import Data.Bitraversable ( bitraverse ) +import Data.Foldable ( traverse_ ) +import Data.IORef +import Data.Validation ( fromEither + , toEither + ) +import Hedgehog +import qualified Hedgehog.Gen as Gen +import qualified Hedgehog.Range as Range +import Refined +import System.Exit ( exitFailure ) + +main :: IO () +main = do + results <- sequence [checkParallel dualTests] + unless (and results) exitFailure + +dualTests :: Group +dualTests = $$(discover) + +prop_parMap2_on_success :: Property +prop_parMap2_on_success = property $ do + a <- forAll $ Gen.int (Range.linear 18 100) + n <- forAll $ Gen.list (Range.linear 1 50) Gen.alpha + let result = parMap2 (ref a) (ref n) Person + expected = Person <$> ref a <*> ref n + result === expected + +prop_parMap2_accumulates_errors :: Property +prop_parMap2_accumulates_errors = property $ do + a <- forAll $ Gen.int (Range.linear 0 17) + n <- forAll $ Gen.list (Range.linear 0 0) Gen.alpha + let + res1 = parMap2 (ref a) (ref n) Person + res2 = Person <$> ref a <*> ref n + exp1 = Left + [ "The predicate (GreaterThan 17) does not hold: \n Value is not greater than 17" + , "The predicate (SizeGreaterThan 0) does not hold: \n Size of Foldable is not greater than 0\n Size is: 0" + ] + exp2 = left (take 1) exp1 + res1 === exp1 + res2 === exp2 + +prop_parTraverse_accumulates_errors :: Property +prop_parTraverse_accumulates_errors = property $ do + xs <- forAll $ Gen.list (Range.linear 1 10) (Gen.int (Range.linear 1 10)) + let f :: Int -> Either [String] Int + f n = Left [show n] + res1 = parTraverse f xs + res2 = traverse f xs + exp1 = Left (show <$> xs) + exp2 = Left (take 1 $ show <$> xs) + res1 === exp1 + res2 === exp2 + +-- This one is tricky to test but this seems good enough for now +prop_parTraverse_io_is_concurrent :: Property +prop_parTraverse_io_is_concurrent = withTests (10 :: TestLimit) $ property $ do + xs <- forAll $ Gen.list (Range.linear 15 25) (Gen.int (Range.linear 1 10)) + let f r n = threadDelay (1 * 3000) >> atomicModifyIORef r (\x -> (n : x, n)) + ref1 <- evalIO $ newIORef [] :: PropertyT IO (IORef [Int]) + ref2 <- evalIO $ newIORef [] :: PropertyT IO (IORef [Int]) + evalIO $ parTraverse_ (f ref1) xs + evalIO $ traverse_ (f ref2) xs + res1 <- evalIO $ readIORef ref1 + res2 <- evalIO $ readIORef ref2 + -- Avoid cases where all elements are the same (could prob. be done in a better way) + let exp1 = if and (fmap (== head xs) (tail xs)) then [] else reverse xs + res1 /== exp1 + res2 === reverse xs + +prop_parMap2_on_lists :: Property +prop_parMap2_on_lists = property $ do + xs <- forAll $ Gen.constant [1 .. 5] :: PropertyT IO [Int] + ys <- forAll $ Gen.constant [6 .. 10] :: PropertyT IO [Int] + let res1 = parMap2 xs ys (+) + res2 = (+) <$> xs <*> ys + exp1 = [7, 9, 11, 13, 15] + exp2 = [7 .. 11] ++ [8 .. 12] ++ [9 .. 13] ++ [10 .. 14] ++ [11 .. 15] + res1 === exp1 + res2 === exp2 + +prop_parBitraverse :: Property +prop_parBitraverse = property $ do + a <- forAll $ Gen.list (Range.linear 5 10) Gen.alpha + b <- forAll $ Gen.int (Range.linear 5 10) + c <- forAll Gen.bool + let res1 = parBitraverse show show (a, b, c) + res2 = bitraverse show show (a, b, c) + length res1 === min (length $ show b) (length $ show c) + length res2 === length (show b) * length (show c) + +-------------- Datatypes ------------------------- + +type Name = Refined NonEmpty String +type Age = Refined (GreaterThan 17) Int + +data Person = Person + { personAge :: Age + , personName :: Name + } deriving (Eq, Show) + +-------------- Sequential Validation ------------- + +mkPersonSeq :: Int -> String -> Either RefineException Person +mkPersonSeq a n = do + age <- refine a + name <- refine n + return $ Person age name + +-------------- Parallel Validation (manually) ------------------- + +type Eff a = Either [String] a + +ref :: Predicate p x => x -> Eff (Refined p x) +ref x = left (\e -> [show e]) (refine x) + +mkPerson :: Int -> String -> Eff Person +mkPerson a n = toEither $ Person <$> fromEither (ref a) <*> fromEither (ref n) + +-------------- Parallel Validation ------------- + +makePerson :: Int -> String -> Eff Person +makePerson a n = parMap2 (ref a) (ref n) Person