diff --git a/CHANGELOG.md b/CHANGELOG.md new file mode 100644 --- /dev/null +++ b/CHANGELOG.md @@ -0,0 +1,13 @@ +Change log +========== + +co-log uses [PVP Versioning][1]. +The change log is available [on GitHub][2]. + +0.0.0 +===== +* Initially created. + +[1]: https://pvp.haskell.org +[2]: https://github.com/kowainik/co-log/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/co-log-core.cabal b/co-log-core.cabal new file mode 100644 --- /dev/null +++ b/co-log-core.cabal @@ -0,0 +1,33 @@ +name: co-log-core +version: 0.0.0 +description: Logging library +synopsis: Logging library +homepage: https://github.com/kowainik/co-log +bug-reports: https://github.com/kowainik/co-log/issues +license: MPL-2.0 +license-file: LICENSE +author: Kowainik +maintainer: xrom.xkov@gmail.com +copyright: 2018 Kowainik +category: Logging +build-type: Simple +extra-doc-files: CHANGELOG.md +cabal-version: 2.0 +tested-with: GHC == 8.4.3 + +source-repository head + type: git + location: https://github.com/kowainik/co-log.git + +library + hs-source-dirs: src + exposed-modules: Colog.Core + Colog.Core.Action + Colog.Core.Class + Colog.Core.Severity + + ghc-options: -Wall -fhide-source-paths + build-depends: base >= 4.11 && < 5 + + default-language: Haskell2010 + default-extensions: InstanceSigs diff --git a/src/Colog/Core.hs b/src/Colog/Core.hs new file mode 100644 --- /dev/null +++ b/src/Colog/Core.hs @@ -0,0 +1,9 @@ +module Colog.Core + ( module Colog.Core.Action + , module Colog.Core.Class + , module Colog.Core.Severity + ) where + +import Colog.Core.Action +import Colog.Core.Class +import Colog.Core.Severity diff --git a/src/Colog/Core/Action.hs b/src/Colog/Core/Action.hs new file mode 100644 --- /dev/null +++ b/src/Colog/Core/Action.hs @@ -0,0 +1,314 @@ +{-# LANGUAGE ViewPatterns #-} + +{- | Implements core data types and combinators for logging actions. +-} + +module Colog.Core.Action + ( -- * Core type and instances + LogAction (..) + + -- * 'Semigroup' combinators + , foldActions + + -- * Contravariant combinators + , cfilter + , cmap + , (>$<) + , (>$) + , cbind + + -- * Divisible combinators + , divide + , conquer + , (>*<) + , (>*) + , (*<) + + -- * Decidable combinators + , lose + , choose + , (>|<) + + -- * Comonadic combinators + , extract + , extend + , (=>>) + , (<<=) + ) where + +import Control.Monad (when, (>=>)) +import Data.Foldable (for_) +import Data.List.NonEmpty (NonEmpty (..)) +import Data.Monoid (Monoid (..)) +import Data.Semigroup (Semigroup (..), stimesMonoid) +import Data.Void (Void, absurd) + +---------------------------------------------------------------------------- +-- Core data type with instances +---------------------------------------------------------------------------- + +{- | Polymorphic and very general logging action type. + +* @__msg__@ type variables is an input for logger. It can be 'Text' or custom +logging messsage with different fields that you want to format in future. + +* @__m__@ type variable is for monadic action inside which logging is happening. It +can be either 'IO' or some custom pure monad. + +Key design point here is that 'LogAction' is: + +* 'Semigroup' +* Contravariant +* Comonad +-} +newtype LogAction m msg = LogAction + { unLogAction :: msg -> m () + } + +{- | This instance allows you to join multiple logging actions into single one. + +For example, if you have two actions like these: + +@ +logToStdout :: 'LogAction' IO String -- outputs String to terminal +logToFile :: 'LogAction' IO String -- appends String to some file +@ + +You can create new 'LogAction' that perform both actions one after another using 'Semigroup': + +@ +logToBoth :: 'LogAction' IO String -- outputs String to both terminal and some file +logToBoth = logToStdout <> logToFile +@ +-} +instance Applicative m => Semigroup (LogAction m a) where + (<>) :: LogAction m a -> LogAction m a -> LogAction m a + LogAction action1 <> LogAction action2 = LogAction $ \a -> action1 a *> action2 a + {-# INLINE (<>) #-} + + sconcat :: NonEmpty (LogAction m a) -> LogAction m a + sconcat = foldActions + {-# INLINE sconcat #-} + + stimes :: Integral b => b -> LogAction m a -> LogAction m a + stimes = stimesMonoid + {-# INLINE stimes #-} + +instance Applicative m => Monoid (LogAction m a) where + mappend :: LogAction m a -> LogAction m a -> LogAction m a + mappend = (<>) + {-# INLINE mappend #-} + + mempty :: LogAction m a + mempty = LogAction $ \_ -> pure () + {-# INLINE mempty #-} + + mconcat :: [LogAction m a] -> LogAction m a + mconcat = foldActions + {-# INLINE mconcat #-} + +---------------------------------------------------------------------------- +-- Combinators +---------------------------------------------------------------------------- + +{- | Joins some 'Foldable' of 'LogAction's into single 'LogAction' using +'Semigroup' instance for 'LogAction'. This is basically specialized version of +'Data.Foldable.fold' function. +-} +foldActions :: (Foldable t, Applicative m) => t (LogAction m a) -> LogAction m a +foldActions actions = LogAction $ \a -> for_ actions $ \(LogAction action) -> action a +{-# INLINE foldActions #-} +{-# SPECIALIZE foldActions :: Applicative m => [LogAction m a] -> LogAction m a #-} +{-# SPECIALIZE foldActions :: Applicative m => NonEmpty (LogAction m a) -> LogAction m a #-} + +{- | Takes predicate and performs given logging action only if predicate returns +'True' on input logging message. +-} +cfilter :: Applicative m => (msg -> Bool) -> LogAction m msg -> LogAction m msg +cfilter predicate (LogAction action) = LogAction $ \a -> when (predicate a) (action a) +{-# INLINE cfilter #-} + +{- | This combinator is @contramap@ from contravariant functor. It is useful +when you have something like + +@ +__data__ LogRecord = LR + { lrName :: LoggerName + , lrMessage :: Text + } +@ + +and you need to provide 'LogAction' which consumes @LogRecord@ + +@ +logRecordAction :: 'LogAction' m LogRecord +@ + +when you only have action that consumes 'Text' + +@ +logTextAction :: 'LogAction' m Text +@ + +With 'cmap' you can do the following: + +@ +logRecordAction :: 'LogAction' m LogRecord +logRecordAction = 'cmap' lrMesssage logTextAction +@ + +This action will print only @lrMessage@ from @LogRecord@. But if you have +formatting function like this: + +@ +formatLogRecord :: LogRecord -> Text +@ + +you can apply it instead of @lrMessage@ to log formatted @LogRecord@ as 'Text'. +-} +cmap :: (a -> b) -> LogAction m b -> LogAction m a +cmap f (LogAction action) = LogAction (action . f) +{-# INLINE cmap #-} + +-- | Operator version of 'cmap'. +infixr 3 >$< +(>$<) :: (a -> b) -> LogAction m b -> LogAction m a +(>$<) = cmap +{-# INLINE (>$<) #-} + +{- | This combinator is @>$@ from contravariant functor. Replaces all locations +in the output with the same value. The default definition is +@contramap . const@, so this is a more efficient version. +-} +infixl 4 >$ +(>$) :: b -> LogAction m b -> LogAction m a +(>$) b (LogAction action) = LogAction (\_ -> action b) + +{- | 'cbind' combinator is similar to 'cmap' but allows to call monadic +functions (functions that require extra context) to extend consumed value. +Consider the following example. + +You have this logging record: + +@ +__data__ LogRecord = LR + { lrTime :: UTCTime + , lrMessage :: Text + } +@ + +and you also have logging consumer inside 'IO' for such record: + +@ +logRecordAction :: 'LogAction' IO LogRecord +@ + +But you need to return consumer only for 'Text' messages: + +@ +logTextAction :: 'LogAction' IO Text +@ + +If you have function that can extend 'Text' to @LogRecord@ like the function +below: + +@ +withTime :: 'Text' -> 'IO' LogRecord +withTime msg = __do__ + time <- getCurrentTime + pure (LR time msg) +@ + +you can achieve desired behavior with 'cbind' in the following way: + +@ +logTextAction :: 'LogAction' IO Text +logTextAction = 'cbind' withTime myAction +@ +-} +cbind :: Monad m => (a -> m b) -> LogAction m b -> LogAction m a +cbind f (LogAction action) = LogAction (f >=> action) +{-# INLINE cbind #-} + +-- | @divide@ combinator from @Divisible@ type class. +divide :: (Applicative m) => (a -> (b, c)) -> LogAction m b -> LogAction m c -> LogAction m a +divide f (LogAction actionB) (LogAction actionC) = LogAction $ \(f -> (b, c)) -> + actionB b *> actionC c + +-- | @conquer@ combinator from @Divisible@ type class. +conquer :: Applicative m => LogAction m a +conquer = LogAction $ const (pure ()) + + +-- | Operator version of @'divide' 'id'@. +infixr 4 >*< +(>*<) :: (Applicative m) => LogAction m a -> LogAction m b -> LogAction m (a, b) +(LogAction actionA) >*< (LogAction actionB) = LogAction $ \(a, b) -> + actionA a *> actionB b +{-# INLINE (>*<) #-} + +infixr 4 >* +(>*) :: Applicative m => LogAction m a -> LogAction m () -> LogAction m a +(LogAction actionA) >* (LogAction actionB) = LogAction $ \a -> + actionA a *> actionB () +{-# INLINE (>*) #-} + +infixr 4 *< +(*<) :: Applicative m => LogAction m () -> LogAction m a -> LogAction m a +(LogAction actionA) *< (LogAction actionB) = LogAction $ \a -> + actionA () *> actionB a +{-# INLINE (*<) #-} + +-- | @lose@ combinator from @Decidable@ type class. +lose :: (a -> Void) -> LogAction m a +lose f = LogAction (absurd . f) + +-- | @choose@ combinator from @Decidable@ type class. +choose :: (a -> Either b c) -> LogAction m b -> LogAction m c -> LogAction m a +choose f (LogAction actionB) (LogAction actionC) = LogAction (either actionB actionC . f) + +-- | Operator version of @'choose' 'id'@. +infixr 3 >|< +(>|<) :: LogAction m a -> LogAction m b -> LogAction m (Either a b) +(LogAction actionA) >|< (LogAction actionB) = LogAction (either actionA actionB) +{-# INLINE (>|<) #-} + +{- | If @msg@ is 'Monoid' then 'extract' performs given log action by passing +'mempty' to it. +-} +extract :: Monoid msg => LogAction m msg -> m () +extract action = unLogAction action mempty + +-- TODO: write better motivation for comonads +{- | This is a /comonadic extend/. It allows you to chain different transformations on messages. + +>>> logToStdout = LogAction putStrLn +>>> f (LogAction l) = l ".f1" *> l ".f2" +>>> g (LogAction l) = l ".g" +>>> unLogAction logToStdout "foo" +foo +>>> unLogAction (extend f logToStdout) "foo" +foo.f1 +foo.f2 +>>> unLogAction (extend g $ extend f logToStdout) "foo" +foo.g.f1 +foo.g.f2 +>>> unLogAction (logToStdout =>> f =>> g) "foo" +foo.g.f1 +foo.g.f2 + +-} +extend :: Semigroup msg => (LogAction m msg -> m ()) -> LogAction m msg -> LogAction m msg +extend f (LogAction action) = LogAction $ \m -> f $ LogAction $ \m' -> action (m <> m') + +-- | 'extend' with the arguments swapped. Dual to '>>=' for a 'Monad'. +infixl 1 =>> +(=>>) :: Semigroup msg => LogAction m msg -> (LogAction m msg -> m ()) -> LogAction m msg +(=>>) = flip extend +{-# INLINE (=>>) #-} + +-- | 'extend' in operator form. +infixr 1 <<= +(<<=) :: Semigroup msg => (LogAction m msg -> m ()) -> LogAction m msg -> LogAction m msg +(<<=) = extend +{-# INLINE (<<=) #-} diff --git a/src/Colog/Core/Class.hs b/src/Colog/Core/Class.hs new file mode 100644 --- /dev/null +++ b/src/Colog/Core/Class.hs @@ -0,0 +1,28 @@ +{-# LANGUAGE FlexibleInstances #-} +{-# LANGUAGE MultiParamTypeClasses #-} + +{- | Provides type class for objects that has access to 'LogAction'. +-} + +module Colog.Core.Class + ( HasLog (..) + , overLogAction + ) where + +import Colog.Core.Action (LogAction) + +{- | This types class contains simple pair of getter-setter. + +TODO: laws +-} +class HasLog env msg m where + getLogAction :: env -> LogAction m msg + setLogAction :: LogAction m msg -> env -> env + +instance HasLog (LogAction m msg) msg m where + getLogAction = id + setLogAction = const + +overLogAction :: HasLog env msg m => (LogAction m msg -> LogAction m msg) -> env -> env +overLogAction over env = setLogAction (over $ getLogAction env) env +{-# INLINE overLogAction #-} diff --git a/src/Colog/Core/Severity.hs b/src/Colog/Core/Severity.hs new file mode 100644 --- /dev/null +++ b/src/Colog/Core/Severity.hs @@ -0,0 +1,57 @@ +{-# LANGUAGE PatternSynonyms #-} + +{- | This module introduces 'Severity' data type for expressing how severe the +message is. Also, it contains useful functions for work with 'Severity'. + +-} + +module Colog.Core.Severity + ( Severity (..) + -- Patterns + , pattern D + , pattern I + , pattern W + , pattern E + , filterBySeverity + ) where + +import Data.Ix (Ix) + +import Colog.Core.Action (LogAction (..), cfilter) + +-- | Severity for the log messages. +data Severity + {- | Information useful for debug purposes. + + E.g. output of the function that is important for the internal development, + not for users. Like, the result of SQL query. + -} + = Debug + {- | Normal operational information. + + E.g. describing general steps: starting application, finished downloading. + -} + | Info + {- | General warnings, non-critical failures. + + E.g. couldn't download icon from some service to display. + -} + | Warning + {- | General errors/severe errors. + + E.g. exceptional situations: couldn't syncronize accounts. + -} + | Error + deriving (Show, Read, Eq, Ord, Enum, Bounded, Ix) + +pattern D, I, W, E :: Severity +pattern D <- Debug where D = Debug +pattern I <- Info where I = Info +pattern W <- Warning where W = Warning +pattern E <- Error where E = Error +{-# COMPLETE D, I, W, E #-} + + +-- | Filters messages by given 'Severity'. +filterBySeverity :: Applicative m => Severity -> (a -> Severity) -> LogAction m a -> LogAction m a +filterBySeverity s fs = cfilter (\a -> fs a >= s)