commit 5ee60fd527d55ef47e2e708e25b8746d9f3176ab
Author: Lucas DiCioccio <lucas@dicioccio.fr>
Date:   Tue May 3 00:20:50 2022 +0200

    implement dhall section-loader

diff --git a/blog.cabal b/blog.cabal
index bce6429..d7d9ed3 100644
--- a/blog.cabal
+++ b/blog.cabal
@@ -50,6 +50,7 @@ executable blog
                     , bytestring
                     , containers
                     , directory
+                    , dhall
                     , filepath
                     , process-extras
                     , text
diff --git a/src/Blog/Prelude.hs b/src/Blog/Prelude.hs
index 8b660c7..f0cee00 100644
--- a/src/Blog/Prelude.hs
+++ b/src/Blog/Prelude.hs
@@ -29,7 +29,7 @@ import Data.Bool (Bool(..), not)
 import Data.Coerce (Coercible, coerce)
 import Data.Eq (Eq, (==), (/=))
 import Data.Either (Either(..), either)
-import Data.Foldable (traverse_)
+import Data.Foldable (Foldable(..), traverse_)
 import Data.Function (($), (.), const, flip)
 import Data.Functor ((<$>))
 import Data.Int (Int)
@@ -38,7 +38,7 @@ import Data.Maybe (Maybe(..), maybe)
 import Data.Monoid (Monoid, mappend, mempty, mconcat)
 import Data.Ord (Ord, compare)
 import Data.Semigroup (Semigroup(..), (<>))
-import Data.Traversable (traverse)
+import Data.Traversable (Traversable(..), traverse)
 import Data.Tuple (uncurry, fst, snd)
 import Control.Monad (Monad, Functor, void, fmap, (>>), (>>=), (=<<))
 import Control.Applicative (Applicative, pure, (<*>), (*>), (<*), (<|>))
diff --git a/src/Blog/Section.hs b/src/Blog/Section.hs
index 3a02c2a..bad6855 100644
--- a/src/Blog/Section.hs
+++ b/src/Blog/Section.hs
@@ -1,4 +1,5 @@
 {-# LANGUAGE DeriveFunctor #-}
+{-# LANGUAGE DeriveTraversable #-}
 
 module Blog.Section (SectionType(..), Format(..), Section(..), extract, extract', section, sectionType, Parser)
 where
@@ -24,6 +25,7 @@ data SectionType
 
 data Format
   = Cmark
+  | Dhall
   | Json
   | TextHtml
   | Css
@@ -32,7 +34,7 @@ data Format
 
 data Section a
   =  Section SectionType Format a
-  deriving (Show, Eq, Ord, Functor)
+  deriving (Show, Eq, Ord, Functor, Foldable, Traversable)
 
 extract' :: Coercible a b => Section a -> b
 extract' (Section _ _ a) = coerce a
@@ -57,11 +59,12 @@ sectionType =
     generator = string "generator:cmd" *> pure GeneratorInstructions
 
 format :: Parser Format
-format = cmark <|> json <|> css
+format = cmark <|> json <|> css <|> dhall
   where
     cmark = string "cmark" *> pure Cmark
     json = string "json" *> pure Json
     css = string "css" *> pure Css
+    dhall = string "dhall" *> pure Dhall
 
 section :: Parser (Section [Text])
 section = f <$> (headers <?> "section-headers") <*> body
diff --git a/src/Blog/Site.hs b/src/Blog/Site.hs
index eac82b3..3a3d082 100644
--- a/src/Blog/Site.hs
+++ b/src/Blog/Site.hs
@@ -11,6 +11,11 @@ data Article a
   = Article FilePath [Section a]
   deriving (Show, Eq, Ord, Functor)
 
+-- A lens-like over-function that effectfully alters sections of an article.
+overSections :: (Applicative t) => (Section a -> t (Section b)) -> Article a -> t (Article b)
+overSections f (Article p xs) =
+  Article p <$> traverse f xs
+
 data VideoFile = VideoFile
   deriving (Show, Eq, Ord)
 
diff --git a/src/Blog/SiteLoader.hs b/src/Blog/SiteLoader.hs
index 7864da9..6c4587c 100644
--- a/src/Blog/SiteLoader.hs
+++ b/src/Blog/SiteLoader.hs
@@ -3,12 +3,15 @@ module Blog.SiteLoader (module Blog.Site, loadSite, LogMsg(..))where
 
 import Control.Exception (throwIO)
 import Data.Text (Text)
+import qualified Data.Text as Text
 import qualified Data.Text.IO as Text
 import qualified Data.List as List
 import Text.Megaparsec
 import Text.Megaparsec.Char (newline)
 import System.Directory (listDirectory)
 import System.FilePath.Posix ((</>), takeExtension)
+import Dhall (input)
+import Dhall.Marshal.Decode (list, strictText)
 
 import Blog.Prelude
 import Blog.Target
@@ -23,6 +26,7 @@ data LogMsg
   | LoadCss FilePath
   | LoadJs FilePath
   | LoadDotSource FilePath
+  | EvalSection FilePath SectionType Format
   deriving Show
 
 article :: FilePath -> Parser (Article [Text])
@@ -34,8 +38,18 @@ loadArticle :: Loader (Article [Text])
 loadArticle trace path = do
   trace $ LoadArticle path
   eart <- runParser (article path) path <$> Text.readFile path
-  let src a = Sourced (FileSource path) a
-  either throwIO (pure . src) eart
+  case eart of
+    Left err -> throwIO err
+    Right art -> Sourced (FileSource path) <$> overSections (evalSection path trace) art
+
+
+evalSection :: FilePath -> (LogMsg -> IO ()) -> Section [Text] -> IO (Section [Text])
+evalSection path trace x@(Section t fmt body) = do
+  trace $ EvalSection path t fmt
+  case fmt of
+    Dhall -> do
+      Section t Cmark <$> input (list strictText) (Text.unlines body)
+    _ -> pure x
 
 loadImage :: Loader Image
 loadImage trace path = do
diff --git a/src/Blog/Wordcount.hs b/src/Blog/Wordcount.hs
index 321067b..96e8033 100644
--- a/src/Blog/Wordcount.hs
+++ b/src/Blog/Wordcount.hs
@@ -6,7 +6,6 @@ module Blog.Wordcount where
 import qualified Commonmark
 import Data.Text (Text)
 import qualified Data.Text as Text
-import Data.List (sum)
 
 import Blog.Target
 import Blog.Section