error-list (empty) → 0.1.0.0

raw patch · 4 files changed

+172/−0 lines, 4 filesdep +basedep +mtldep +textsetup-changed

Dependencies added: base, mtl, text, text-render

Files

LICENSE +20/−0
Setup.hs +2/−0
error-list.cabal +25/−0
src/Control/Exception/ErrorList.hs +125/−0

+ LICENSE view

@@ -0,0 +1,20 @@+Copyright (c) 2014 Allen Nelson++Permission is hereby granted, free of charge, to any person obtaining+a copy of this software and associated documentation files (the+"Software"), to deal in the Software without restriction, including+without limitation the rights to use, copy, modify, merge, publish,+distribute, sublicense, and/or sell copies of the Software, and to+permit persons to whom the Software is furnished to do so, subject to+the following conditions:++The above copyright notice and this permission notice shall be included+in all copies or substantial portions of the Software.++THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,+EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF+MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.+IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY+CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,+TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE+SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

+ Setup.hs view

@@ -0,0 +1,2 @@+import Distribution.Simple+main = defaultMain

+ error-list.cabal view

@@ -0,0 +1,25 @@+-- Initial error-list.cabal generated by cabal init.  For further+-- documentation, see http://haskell.org/cabal/users-guide/++name:                error-list+version:             0.1.0.0+synopsis:            A useful type for collecting error messages.+-- description:+homepage:            http://github.com/thinkpad20/error-list+license:             MIT+license-file:        LICENSE+author:              Allen Nelson+maintainer:          ithinkican@gmail.com+-- copyright:+category:            Control+build-type:          Simple+-- extra-source-files:+cabal-version:       >=1.10++library+  exposed-modules:     Control.Exception.ErrorList+  -- other-modules:+  other-extensions:    LambdaCase, OverloadedStrings, NoMonomorphismRestriction, FlexibleContexts, TypeSynonymInstances, FlexibleInstances, ViewPatterns, NoImplicitPrelude, TypeFamilies+  build-depends:       base >=4.8 && <4.9, mtl, text, text-render+  hs-source-dirs:      src+  default-language:    Haskell2010

+ src/Control/Exception/ErrorList.hs view

@@ -0,0 +1,125 @@+{-# LANGUAGE OverloadedStrings #-}+{-# LANGUAGE FlexibleContexts #-}+{-# LANGUAGE NoImplicitPrelude #-}+{-# LANGUAGE TypeFamilies #-}+module Control.Exception.ErrorList (+    ErrorList(..), EList(..),+    throwError1, throwErrorC, addError1, addErrorC,+    assert, assertC, wrapJust, withHandler, ifErrorDo, ifErrorReturn,+    showError, showError', errorC, oneErrorC, firstSuccess,+    inContext+  ) where++import qualified Prelude as P+import Prelude (($), (.), map, Int, Double, Functor(..), Show(..),+                Eq(..), Bool(..), Integer, Double, Monad(..), flip,+                Maybe(..), Either(..), IO(..))+import Control.Monad (liftM)+import Control.Monad.Trans (MonadIO(..), lift)+import Control.Monad.Except (ExceptT, MonadError(..), throwError, runExceptT)+import Control.Applicative hiding (empty)+import Data.Monoid+import Data.Text (Text, pack, unpack)+import qualified Data.Text as T+import qualified GHC.Exts as Exts+import Text.Render++class Exts.IsList elist => ErrorList elist where+  addError :: Text -> elist -> elist+  oneError :: Text -> elist++data EList = EList Text [Text] deriving (Show, Eq)++instance Exts.IsList EList where+  type Item EList = Text+  fromList (e:es) = EList e es+  fromList _ = P.error "No main message in error list"+  toList (EList msg msgs) = msg:msgs++instance ErrorList EList where+  addError e (EList e' es) = EList e (e':es)+  oneError e = EList e []++--instance Monoid ErrorList where+--  mempty = ErrorList mempty+--  ErrorList el1 `mappend` ErrorList el2 = ErrorList (el1 <> el2)++instance Render EList where+  render (EList m msgs) = T.unlines $ "Error:" : map (sp <>) (m:msgs)+    where sp = T.replicate 2 " "++-- | Throws a single-message eror list.+throwError1 :: (ErrorList e, MonadError e m) => Text -> m a+throwError1 = throwError . oneError++-- | Concatenates a list of strings and throws them as an error.+throwErrorC :: (ErrorList e, MonadError e m) => [Text] -> m a+throwErrorC = throwError1 . mconcat++-- | Throws a new error with the given string added on.+addError1 :: (ErrorList e, MonadError e m) => Text -> e -> m a+addError1 msg = throwError . addError msg++-- | Throws a new error with the concatenation of the argument added on.+addErrorC :: (ErrorList e, MonadError e m) => [Text] -> e -> m a+addErrorC list = addError1 (mconcat list)++-- | Useful when the handler is more concise than the action.+withHandler :: MonadError e m => (e -> m a) -> m a -> m a+withHandler = flip catchError++-- | Tries something and throws an error if it fails.+inContext :: (ErrorList e, MonadError e m) => Text -> m a -> m a+inContext ctx action = action `catchError` addError1 ctx++-- | Wraps a successful result in a `Just` and a failure in a `Nothing`.+wrapJust :: MonadError e m => m a -> m (Maybe a)+wrapJust action = liftM Just action `ifErrorReturn` Nothing++-- | Performs an action, returning the second argument if it fails.+ifErrorReturn :: MonadError e m => m a -> a -> m a+ifErrorReturn action a = action `ifErrorDo` return a++-- | Specifies what to do if the given action fails.+ifErrorDo :: MonadError e m => m a -> m a -> m a+ifErrorDo action action' = action `catchError` \_ -> action'++-- | If the test is false, throws an error with the given message.+assert :: (ErrorList e, MonadError e m) => Bool -> Text -> m ()+assert True _ = return ()+assert False msg = throwError1 msg++-- | Same as `assert`, but concatenates a text list.+assertC :: (ErrorList e, MonadError e m) => Bool -> [Text] -> m ()+assertC test = assert test . mconcat++-- | Pretty-prints errors that use `Either`.+showError :: (Render e, Render b) => (a -> Either e b) -> a -> IO ()+showError func arg = case func arg of+  Left e -> P.putStrLn $ unpack $ render e+  Right x -> P.putStrLn $ unpack $ render x++-- | Pretty-prints errors that use `Either`, appearing in tuples.+showError' :: (Render e, Render b) => (a -> (Either e b, c)) -> a -> IO ()+showError' func arg = case func arg of+  (Left e, _) -> P.putStrLn $ unpack $ render e+  (Right x, _) -> P.putStrLn $ unpack $ render x++-- | Concatenates a list of `Text` and makes an error out of it.+errorC :: [Text] -> a+errorC = P.error . unpack . mconcat++firstSuccess :: (ErrorList e, MonadError e m) => Text -> [m a] -> m a+firstSuccess msg [] = throwError1 msg+firstSuccess msg (a:as) = a `ifErrorDo` firstSuccess msg as++-- | Pretty-prints an error list. Considers the first item of the list to+-- be the "main" message; subsequent messages are listed after.+--printErrors :: ErrorList e => e -> IO ()+--printErrors (ErrorList err errs) = do+--  P.putStrLn ("Error: " <> unpack err)+--  P.mapM_ (P.putStrLn . unpack . ("  " <>)) errs++-- | Same as `oneError` but concatenates its argument.+oneErrorC :: ErrorList e => [Text] -> e+oneErrorC = oneError . mconcat