Add some more guidance:

- Indication that you need to complete the `FromRow` instance.
- Construction of the `DBComment` type.

level04/src/FirstApp/DB.hs

@@ -32,7 +32,12 @@ import           FirstApp.Types                     (Comment, CommentText,
 -- our database queries. This also allows things to change over time without
 -- having to rewrite all of the functions that need to interact with DB related
 -- things in different ways.
+--
+-- To help with that, we create a new data type that can hold our `Connection`
+-- for us, and allows it to be expanded later if we need to
 data FirstAppDB = FirstAppDB
+  { dbConn :: Connection
+  }
 
 -- Quick helper to pull the connection and close it down.
 closeDB

level04/src/FirstApp/DB/Types.hs

@@ -10,16 +10,19 @@ import           Database.SQLite.Simple.FromRow (FromRow (fromRow), field)
 -- application, we create a stand alone type that will represent the data we
 -- store in the database. In this instance, it is the raw types that make up a
 -- comment.
---
+
 -- Complete in the DbComment type below so it is a record type that matches the
--- Comment type, but without the newtype wrappers for each value.
+-- Comment type, but without the newtype wrappers for each value. To get started,
+-- just copy the new definition for the `Comment` type from FirstApp.Types.
 data DBComment = DBComment
-  deriving Show
+  -- NB: Haskell does not allow duplicate field names for records so the field
+  -- names for this type will have to be slightly different
 
 -- This Typeclass comes from the `sqlite-simple` package and describes how to
 -- decode a single row from the database into a single representation of our
 -- type. This technique of translating a result row to a type will differ
 -- between different packages/databases.
 instance FromRow DBComment where
+  fromRow = error "FromRow DBComment instance not implemented"
 
 -- Now move to ``src/FirstApp/Types.hs``