Restructured the Types.hs a bit to help with flow

level02/src/FirstApp/Main.hs

@@ -17,9 +17,9 @@ import           Data.Text.Encoding       (decodeUtf8)
 import           FirstApp.Types
 
 
--- |------------------------------------------------------|
--- | Don't start here, go straight to FirstApp.Types! :)  |
--- |------------------------------------------------------|
+-- ---------------------------------------------|
+--  Don't start here, go to FirstApp.Types! :)  |
+-- ---------------------------------------------|
 
 runApp :: IO ()
 runApp = run 3000 app
@@ -65,6 +65,7 @@ mkRequest rq =
 -- These helpers will take the raw request information and turn it into
 -- one of our data types. This means we draw a line about where the unruly outside
 -- world must end, and where the well-typed world of our application begins.
+
 mkAddRequest
   :: Text
   -> LBS.ByteString
@@ -75,25 +76,27 @@ mkAddRequest ti c =
 -- This has other benefits, we're able isolate our validation requirements into the
 -- smallest chunks we can manage. This allows for fantastic reuse and it also means
 -- that validation is not spread across the application. It is kept at the borders.
+
 mkViewRequest
   :: Text
   -> Either Error RqType
 mkViewRequest =
   error "mkViewRequest not implemented"
 
--- Even thought it may seem trivial or even pointless to write functions such as these
--- it allows for much greater consistency across the application.
-
--- These are straight forward data constructors, but by doing it this way we don't
--- have any snowflakes littered about the code. It also enhances our ability to
--- spot larger patterns in our application, which are opportunities for abstraction.
+-- Even though it may seem too trivial or even pointless to write functions such
+-- as these it allows for much greater consistency across the application.
+--
+-- Some of these are straight forward data constructors, but by doing it this
+-- way we don't have any snowflakes littered about the code. It also enhances
+-- our ability to spot larger patterns in our application, which are
+-- opportunities for abstraction.
 mkListRequest
   :: Either Error RqType
 mkListRequest =
   error "mkListRequest not implemented"
 
 {-|
-HALP
+HALP - wording - is it useful?
 
 Alternative type sig:
 Either Error a
@@ -112,20 +115,17 @@ mkErrorResponse
 mkErrorResponse _ =
   error "mkErrorResponse not implemented"
 
-{-|
-We'll stub these for now as the general structure and the process of reaching
-this stage is the more important lesson here.
-
-Notice how we're only accepting our predefined request types that have the required
-information already validated and prepared for use in the handling of the request.
-
-If we find that we need more information to handle a request, or we have a new
-type of request that we'd like to handle then we simply update the RqType structure
-and the compiler will let us know the affected portions of our application.
-
-Reduction of concerns such that each section of the application only deals with
-a small piece is one of the benefits of developing in this way.
--}
+-- Notice how we're only accepting our predefined request types that have the
+-- required information already validated and prepared for use in the handling
+-- of the request.
+--
+-- If we find that we need more information to handle a request, or we have a
+-- new type of request that we'd like to handle then we simply update the RqType
+-- structure and the compiler will let us know the affected portions of our
+-- application.
+--
+-- Reduction of concerns such that each section of the application only deals
+-- with a small piece is one of the benefits of developing in this way.
 handleRequest
   :: RqType
   -> Either Error Response

level02/src/FirstApp/Types.hs

@@ -23,23 +23,33 @@ data RqType
 -- types reflect when errors can be introduced into our program. Additionally
 -- it's useful to be able to be descriptive about what went wrong.
 
--- So lets think about some of the basic things that can wrong with our
--- program and create some values to represent that.
+-- Think about some of the basic things that can wrong with our Requests and
+-- building the RqTypes, and create some values to represent that.
 data Error
+-- For now we don't need to worry about things like malformed requests or
+-- invalid headers etc.
 
 -- Provide a type to list our response content types so we don't try to
 -- do the wrong thing with what we meant to be used as text/JSON etc.
 data ContentType
+--
+-- The ContentType description for a header doesn't match our data definition
+-- so we write a little helper function to pattern match on our ContentType
+-- value and provide the correct header value.
+renderContentType
+  :: ContentType
+  -> ByteString
+renderContentType =
+  error "renderContentType not implemented"
 
 -- In Haskell the `newtype` comes with zero runtime cost. It is purely used for
 -- typechecking. So when you have a bare 'primitive' value, like an Int, String, or
 -- even [a], you can wrap it up in a `newtype` for clarity.
 
--- The type system will check it for you, and the compiler will eliminate the cost
--- once it has passed.
+-- The type system will check it for you, and the compiler will eliminate the cost.
 
 -- Having specialised constructor functions for the newtypes allows you to set
--- restrictions for your newtype.
+-- extra restrictions for your newtype.
 
 -- Write two `newtype` definitions for `Topic` and `CommentText` that wrap a
 -- `Text` value
@@ -52,10 +62,9 @@ data ContentType
 
 -- |
 
--- An additional benefit of `newtype` is that we can choose to not export the
--- constructor and provide a function of our own. In our case, we're not
--- interested in empty `Text` values so we can eliminate them and immediately
--- report an error.
+-- A benefit of `newtype` is that we can choose to *not* export the constructor
+-- and provide a function of our own. In our case, we're not interested in empty
+-- `Text` values so we can eliminate them and immediately report an error.
 mkTopic
   :: Text
   -> Either Error Topic
@@ -69,13 +78,6 @@ mkCommentText =
   error "mkCommentText not implemented"
 
 -- After you've implemented these functions, adjust the export list in the
--- module declaration so your constructor functions cannot be bypassed.
+-- module declaration so your constructor functions cannot be bypassed. Also
+-- export the functions that let you access the inner value of the newtype.
 
--- The ContentType description for a header doesn't match our data definition
--- so we write a little helper function to pattern match on our ContentType
--- value and provide the correct header value.
-renderContentType
-  :: ContentType
-  -> ByteString
-renderContentType =
-  error "renderContentType not implemented"