pretty errors and swapped to ParsecT to do debugging stuff

app/Markdown.hs

@@ -7,16 +7,22 @@ module Markdown where
 
 import Control.Applicative (many, optional, some, (<|>))
 import Control.Monad (guard, void)
+import Control.Monad.Trans.Class (lift)
 import Data.Char (isAlpha)
 import Data.Text (Text)
 import qualified Data.Text as T
 import Data.Void (Void)
 import IR
-import Text.Megaparsec (Parsec, anySingle, anySingleBut, between, choice, count, eof, manyTill, notFollowedBy, satisfy, skipSome, try, (<?>))
+import Text.Megaparsec (ParsecT, anySingle, anySingleBut, between, choice, count, eof, manyTill, notFollowedBy, satisfy, skipSome, try, (<?>))
 import qualified Text.Megaparsec as MP
 import Text.Megaparsec.Char (alphaNumChar, char, digitChar, string)
 
-type Parser = Parsec Void String
+type ParserT m = ParsecT Void String m
+
+type Parser = ParserT IO
+
+log_ :: String -> Parser ()
+log_ = lift . putStrLn
 
 anyChar :: Parser Char
 anyChar = anySingle
@@ -78,10 +84,11 @@ blankLine = do
 headingBlock :: Parser Element
 headingBlock = do
   hashes <- some (char '#') <?> "Heading Hashes"
+  log_ "heading"
   let level = length hashes
   guard (level <= 6) <?> "Higher than level 6"
   many (char ' ' <|> char '\t') <?> "Pre-Text Whitespace"
-  content <- manyTill (inlineElement <?> "Header Text") (try lineEnding <?> "Header Ending")
+  content <- manyTill ((inlineElement <* log_ "element") <?> "Header Text") (try lineEnding <?> "Header Ending")
   pure $ Heading $ H level content
 
 -- Fenced Code Block

app/Utilities.hs

@@ -2,6 +2,7 @@ module Utilities where
 
 import Config
 import Control.Monad (filterM)
+import Control.Monad.IO.Class (liftIO)
 import Data.List (find)
 import Data.Text (Text)
 import qualified Data.Text as T
@@ -15,7 +16,7 @@ import Development.Shake.FilePath ((<.>), (</>))
 import qualified Development.Shake.FilePath as FP
 import HTML
 import Markdown
-import Text.Megaparsec (parse)
+import Text.Megaparsec (errorBundlePretty, runParserT)
 import Types
 
 indexHtmlOutputPath :: FilePath -> FilePath
@@ -37,9 +38,10 @@ indexHtmlMarkdownSourcePath =
 markdownToHtml :: (FromJSON a) => FilePath -> Action (a, Text)
 markdownToHtml filePath = do
   content <- Shake.readFile' filePath
-  let (metadataText, document) = case parse (liftA2 (,) Markdown.metadata Markdown.document) filePath content of
+  parse <- liftIO $ runParserT (liftA2 (,) Markdown.metadata Markdown.document) filePath content
+  let (metadataText, document) = case parse of
         Right (a, b) -> (a, b)
-        Left e -> error $ show e
+        Left e -> error $ errorBundlePretty e
 
   let metadata = case decodeEither' $ encodeUtf8 metadataText of
         Right m -> m
@@ -52,10 +54,10 @@ now = Shake.liftIO $ fmap (T.pack . iso8601Show) getCurrentTime
 markdownToPost :: FilePath -> Action Post
 markdownToPost path = do
   content <- Shake.readFile' path
-  -- TODO: error handling
+  parse <- liftIO $ runParserT Markdown.metadata path content
-  let postData = case parse Markdown.metadata path content of
+  let postData = case parse of
         Right p -> p
-        Left e -> error $ show e
+        Left e -> error $ errorBundlePretty e
   let post = case decodeEither' $ encodeUtf8 postData of
         Right p -> p
         Left e -> error $ show e

psb.cabal

@@ -35,7 +35,7 @@ executable psb
 
     -- Other library packages from which modules are imported.
     -- https://hackage.haskell.org/package/texmath
-    build-depends:    base >=4.17.2.1, mustache >=2.4.2,  shake >= 0.19.8, deriving-aeson >= 0.2.9, aeson, text, time, unordered-containers, yaml, megaparsec >= 9.7.0
+    build-depends:    base >=4.17.2.1, mustache >=2.4.2,  shake >= 0.19.8, deriving-aeson >= 0.2.9, aeson, text, time, unordered-containers, yaml, megaparsec >= 9.7.0, transformers >= 0.6.2
     --parsec >= 3.1.18.0
 
     -- Directories containing source files.