Add mention of fromIntegral function.

Per #28 , added some wording for the `fromIntegral` function.

Removed the 'aside' for `ghcid` as this was causing more problems
than it was solving. Too many install / usage dramas.

Added a snippet for loading a repl with test libraries and packages
loaded. Because I had completely forgotten how to do that.

level03/README.md

@@ -28,54 +28,18 @@ For a stack environment:
 $ stack build --test
 ```
 
+To load the tests in the REPL:
+
+```shell
+# Cabal
+$ cabal repl level04-tests
+
+# Stack
+$ stack ghci level04:level04-tests
+```
+
 Start in ``tests/Test.hs``.
 
 [HSpec]: (http://hspec.github.io/)
 [hspec-wai]: (https://hackage.haskell.org/package/hspec-wai)
 [doctest]: (https://hackage.haskell.org/package/doctest)
-
-#### Aside: Tool Introduction - ghcid
-
-[ghcid]: (https://github.com/ndmitchell/ghcid)
-
-Additionally we'd like to introduce a command line tool that you may find useful
-for Haskell development; [ghcid]. This is a very lightweight tool that works for
-any project with a functioning cabal setup.
-
-If you would like to use it, consult its documentation for how to install it,
-and then in an spare open terminal window, navigate to the root of the Haskell
-project and run ``$ ghcid``.
-
-It will then attempt to build your project, if errors are found they will be
-displayed. But more importantly you can go back to editing files in the project
-and ``ghcid`` will refresh in the background. Providing you with new error
-messages or ``All Good`` if it cannot find any errors.
-
-``ghcid`` provides extremely fast feedback, allowing for a nice development
-process with constant feedback about your changes. It is very useful in tandem
-with type holes. Give it a try!
-
-``ghcid`` can also help out when you're writing your tests. Since normally the
-source and other packages that are listed in a `test-suite` configuration
-section in the Cabal file are not loaded. You can manually tell ``ghcid`` to
-load and examine these files with the following command:
-
-```bash
-$ ghcid -c "cabal repl level03"
-
-# Or for using ghcid to check your tests
-$ ghcid -c "cabal repl level03-tests"
-
-# A note for sandboxed ghcid, you may need to provide an
-# explicit path to the binary:
-$ .cabal-sandbox/bin/ghcid -c "cabal repl level03-tests"
-```
-
-It should work with ``stack`` as well:
-```bash
-$ ghcid -c "stack repl level03-tests"
-```
-
-Please read the ``ghcid``documentation for installation and usage
-instructions. The [FAQ](https://github.com/ndmitchell/ghcid#faq) provides
-some useful tips.

level05/src/FirstApp/Types.hs

@@ -150,6 +150,8 @@ renderContentType JSON      = "application/json"
 -- function in order to get the value out.
 --
 newtype Port = Port
+  -- You will notice we're using ``Word16`` as our type for the ``Port`` value.
+  -- This is because a valid port number can only be a 16bit unsigned integer.
   { getPort :: Word16 }
   deriving (Eq, Show)
 
@@ -157,7 +159,7 @@ newtype DBFilePath = DBFilePath
   { getDBFilePath :: FilePath }
   deriving (Eq, Show)
 
--- The ``Conf`` type will need:
+-- Add some fields to the ``Conf`` type:
 -- - A customisable port number: ``Port``
 -- - A filepath for our SQLite database: ``DBFilePath``
 data Conf = Conf
@@ -166,6 +168,12 @@ data Conf = Conf
 -- values from being used in our application. However Wai is not so stringent.
 -- To accommodate this and make our lives a bit easier, we will write this
 -- helper function to take ``Conf`` value and convert it to an ``Int``.
+--
+-- We'll need to use a function called; ``fromIntegral``, to convert our
+-- ``Word16`` to an ``Int``. The type of this function is:
+--
+-- fromIntegral :: (Num b, Integral a) => a -> b
+--
 confPortToWai
   :: Conf
   -> Int