Support GHC-8.8

Add MonadFail instances and constraints.

9 files changed, 29 insertions, 22 deletions

diff --git a/.gitignore b/.gitignore
index 49f55c1..eab2fac 100644
--- a/.gitignore
+++ b/.gitignore
@@ -11,6 +11,9 @@ tags
 cabal.sandbox.config
 .cabal-sandbox/
 .stack-work
+dist
+dist-*
+.ghc.environment.*
 
 # Ignore test builds.
 tests/Main
diff --git a/CHANGELOG.md b/CHANGELOG.md
index af21933..3f5bb3e 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -4,6 +4,10 @@ title: Releases
 
 # Releases
 
+## Unreleased
+
+- Support GHC-8.8. Add `MonadFail` instances and constraints.
+
 ## Hakyll 4.13.0.1 (2019-09-18)
 
 - Add missing test files (contribution by Justin Humm)
diff --git a/hakyll.cabal b/hakyll.cabal
index 927498c..90ba220 100644
--- a/hakyll.cabal
+++ b/hakyll.cabal
@@ -179,15 +179,15 @@ Library
     lrucache             >= 1.1.1    && < 1.3,
     mtl                  >= 1        && < 2.3,
     network-uri          >= 2.6      && < 2.7,
-    optparse-applicative >= 0.12     && < 0.15,
+    optparse-applicative >= 0.12     && < 0.16,
     parsec               >= 3.0      && < 3.2,
     process              >= 1.6      && < 1.7,
     random               >= 1.0      && < 1.2,
-    regex-tdfa           >= 1.1      && < 1.3,
+    regex-tdfa           >= 1.1      && < 1.4,
     resourcet            >= 1.1      && < 1.3,
     scientific           >= 0.3.4    && < 0.4,
     tagsoup              >= 0.13.1   && < 0.15,
-    template-haskell     >= 2.14     && < 2.15,
+    template-haskell     >= 2.14     && < 2.16,
     text                 >= 0.11     && < 1.3,
     time                 >= 1.8      && < 1.10,
     time-locale-compat   >= 0.1      && < 0.2,
@@ -231,7 +231,7 @@ Library
     Other-Modules:
       Hakyll.Web.Pandoc.Binary
     Build-Depends:
-      pandoc          >= 2.0.5    && < 2.8,
+      pandoc          >= 2.0.5    && < 2.10,
       pandoc-citeproc >= 0.14     && < 0.17
     Cpp-options:
       -DUSE_PANDOC
@@ -326,4 +326,4 @@ Executable hakyll-website
     base      >= 4     && < 5,
     directory >= 1.0   && < 1.4,
     filepath  >= 1.0   && < 1.5,
-    pandoc    >= 2.0.5 && < 2.8
+    pandoc    >= 2.0.5 && < 2.10
diff --git a/lib/Hakyll/Core/Compiler/Internal.hs b/lib/Hakyll/Core/Compiler/Internal.hs
index 762630c..3b62e2d 100644
--- a/lib/Hakyll/Core/Compiler/Internal.hs
+++ b/lib/Hakyll/Core/Compiler/Internal.hs
@@ -40,6 +40,7 @@ module Hakyll.Core.Compiler.Internal
 import           Control.Applicative            (Alternative (..))
 import           Control.Exception              (SomeException, handle)
 import           Control.Monad                  (forM_)
+import qualified Control.Monad.Fail             as Fail
 import           Control.Monad.Except           (MonadError (..))
 import           Data.List.NonEmpty             (NonEmpty (..))
 import qualified Data.List.NonEmpty             as NonEmpty
@@ -183,9 +184,14 @@ instance Monad Compiler where
             CompilerError e       -> return $ CompilerError e
     {-# INLINE (>>=) #-}
 
-    fail = compilerThrow . return
+#if !(MIN_VERSION_base(4,13,0))
+    fail = Fail.fail
     {-# INLINE fail #-}
+#endif
 
+instance Fail.MonadFail Compiler where
+    fail = compilerThrow . return
+    {-# INLINE fail #-}
 
 --------------------------------------------------------------------------------
 instance Applicative Compiler where
diff --git a/lib/Hakyll/Core/Metadata.hs b/lib/Hakyll/Core/Metadata.hs
index 1cf536e..9d99857 100644
--- a/lib/Hakyll/Core/Metadata.hs
+++ b/lib/Hakyll/Core/Metadata.hs
@@ -66,7 +66,7 @@ getMetadataField identifier key = do
 --------------------------------------------------------------------------------
 -- | Version of 'getMetadataField' which throws an error if the field does not
 -- exist.
-getMetadataField' :: MonadMetadata m => Identifier -> String -> m String
+getMetadataField' :: (MonadFail m, MonadMetadata m) => Identifier -> String -> m String
 getMetadataField' identifier key = do
     field <- getMetadataField identifier key
     case field of
diff --git a/lib/Hakyll/Core/Rules/Internal.hs b/lib/Hakyll/Core/Rules/Internal.hs
index 647af74..2617798 100644
--- a/lib/Hakyll/Core/Rules/Internal.hs
+++ b/lib/Hakyll/Core/Rules/Internal.hs
@@ -88,7 +88,7 @@ emptyRulesState = RulesState Nothing Nothing
 -- | The monad used to compose rules
 newtype Rules a = Rules
     { unRules :: RWST RulesRead RuleSet RulesState IO a
-    } deriving (Monad, Functor, Applicative)
+    } deriving (Monad, MonadFail, Functor, Applicative)
 
 
 --------------------------------------------------------------------------------
diff --git a/lib/Hakyll/Web/Template/Context.hs b/lib/Hakyll/Web/Template/Context.hs
index 8627d5b..a5049c2 100644
--- a/lib/Hakyll/Web/Template/Context.hs
+++ b/lib/Hakyll/Web/Template/Context.hs
@@ -365,7 +365,7 @@ dateFieldWith locale key format = field key $ \i -> do
 -- | Parser to try to extract and parse the time from the @published@
 -- field or from the filename. See 'dateField' for more information.
 -- Exported for user convenience.
-getItemUTC :: MonadMetadata m
+getItemUTC :: (MonadMetadata m, MonadFail m)
            => TimeLocale        -- ^ Output time locale
            -> Identifier        -- ^ Input page
            -> m UTCTime         -- ^ Parsed UTCTime
diff --git a/lib/Hakyll/Web/Template/List.hs b/lib/Hakyll/Web/Template/List.hs
index 4d769fc..db3fff1 100644
--- a/lib/Hakyll/Web/Template/List.hs
+++ b/lib/Hakyll/Web/Template/List.hs
@@ -60,7 +60,7 @@ applyJoinTemplateList delimiter tpl context items = do
 --------------------------------------------------------------------------------
 -- | Sort pages chronologically. Uses the same method as 'dateField' for
 -- extracting the date.
-chronological :: MonadMetadata m => [Item a] -> m [Item a]
+chronological :: (MonadMetadata m, MonadFail m) => [Item a] -> m [Item a]
 chronological =
     sortByM $ getItemUTC defaultTimeLocale . itemIdentifier
   where
@@ -71,14 +71,14 @@ chronological =
 
 --------------------------------------------------------------------------------
 -- | The reverse of 'chronological'
-recentFirst :: MonadMetadata m => [Item a] -> m [Item a]
+recentFirst :: (MonadMetadata m, MonadFail m) => [Item a] -> m [Item a]
 recentFirst = liftM reverse . chronological
 
 
 --------------------------------------------------------------------------------
 -- | Version of 'chronological' which doesn't need the actual items.
 sortChronological
-    :: MonadMetadata m => [Identifier] -> m [Identifier]
+    :: (MonadMetadata m, MonadFail m) => [Identifier] -> m [Identifier]
 sortChronological ids =
     liftM (map itemIdentifier) $ chronological [Item i () | i <- ids]
 
@@ -86,6 +86,6 @@ sortChronological ids =
 --------------------------------------------------------------------------------
 -- | Version of 'recentFirst' which doesn't need the actual items.
 sortRecentFirst
-    :: MonadMetadata m => [Identifier] -> m [Identifier]
+    :: (MonadMetadata m, MonadFail m) => [Identifier] -> m [Identifier]
 sortRecentFirst ids =
     liftM (map itemIdentifier) $ recentFirst [Item i () | i <- ids]
diff --git a/stack.yaml b/stack.yaml
index f8a83a4..36891d2 100644
--- a/stack.yaml
+++ b/stack.yaml
@@ -1,4 +1,4 @@
-resolver: lts-13.29
+resolver: lts-15.0
 save-hackage-creds: false
 
 flags:
@@ -23,11 +23,5 @@ build:
   haddock-deps: false
 
 extra-deps:
-- 'cmark-gfm-0.2.0'
-- 'hslua-module-system-0.2.1'
-- 'ipynb-0.1'
-- 'lrucache-1.2.0.1'
-- 'pandoc-2.7.3'
-- 'pandoc-citeproc-0.16.2'
-- 'skylighting-0.8.2'
-- 'skylighting-core-0.8.2'
+- 'http2-1.6.5'
+- 'warp-3.2.28'