Issue Fixes & More feedback driven development

Fixes: #15, #13, #14, #11, #8

Add the IDEAS to a 'Suggestions' section in the FUTURE_PLANS file.

* Updated the cabal instructions for level 03
* Removed the duplicated config loading in level 05
* Add the implementations for File.hs for levels 06 & 07
* Renamed the slightly misleading 'readObject' function
* Fixed the capitalisation of init and close DB functions between levels
  04 & 05.

FUTURE_PLANS.md

@@ -79,3 +79,18 @@ Integration of 'classy mtl' style application design.
 * Build intuition for `AsFoo` & `HasFoo`
 * `mtl` classes are a start, but how do we make this easier?
 * Describe `CanFoo` and introduce `ConstraintKinds`
+
+## Suggestions
+
+* Lens
+* Mocking / Free
+* Dealing with callbacks (more info needed)
+* Streaming / Iteratees (safe resource handling)
+* ST / Safe Mutation techniques
+* Classy MTL
+* Generic / Meta programming
+* Daemons
+* Ermagerd reel librees!
+* Concurrency packages/techniques (book recommendation) - STM
+* Property Based Testing (Hedgehog, advanced testing)
+* Stats

README.md

@@ -29,13 +29,13 @@ IRC on [Freenode](https://freenode.net/) in #qfpl or #fp-course.
 * Have constructed a sequence of goals of increasing difficulty.
 * Have provided a framework within which to apply these goals.
 * Have included relevant components of larger applications:
-  - Package dependencies
-  - Project configuration
-  - Application testing & building
-  - Encoding / Decoding messages (JSON & Binary)
-  - Persistent storage integration
-  - App state & configuration management
-  - Error handling & reporting
+  * Package dependencies
+  * Project configuration
+  * Application testing & building
+  * Encoding / Decoding messages (JSON & Binary)
+  * Persistent storage integration
+  * App state & configuration management
+  * Error handling & reporting
 * Will utilise both type & test driven development techniques.
 * Will explain architectural and design trade-offs when appropriate.
 

level01/README.md

@@ -12,19 +12,19 @@ response and the message "Hello, World!".
 [Hackage]: (https://hackage.haskell.org/)
 [Wai]: (https://hackage.haskell.org/package/wai)
 
-## Running the program:
+## Running the program
 
 To run the application when you are finished:
 
 ```bash
 # With Cabal
-$ cabal exec level01-exe
+$ cabal run level01-exe
 
 # With Stack
 $ stack exec level01-exe
 ```
 
-## Accessing the program:
+## Accessing the program
 
 ```bash
 # Using curl

level02/README.md

@@ -44,7 +44,7 @@ The starting point for this exercise is the ``src/FirstApp/Types.hs``.
 
 ```bash
 # Using cabal
-$ cabal exec level02-exe
+$ cabal run level02-exe
 
 # Using stack
 $ stack exec level02-exe

level03/README.md

@@ -12,6 +12,22 @@ As is to be expected, there are multiple testing frameworks and packages
 available but we will only cover one here. We will use the [HSpec] framework,
 with the [hspec-wai] package to make our lives a bit easier.
 
+### NB: Including Test Library Dependencies
+
+For a cabal sandbox:
+
+```shell
+$ cabal sandbox init
+$ cabal install --only-dependencies --enable-tests
+$ cabal configure --enable-tests
+```
+
+For a stack environment:
+
+```shell
+$ stack build --test
+```
+
 Start in ``tests/Test.hs``.
 
 [HSpec]: (http://hspec.github.io/)
@@ -45,12 +61,21 @@ 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:
-```base
+```bash
 $ ghcid -c "stack repl level03-tests"
 ```
 
-Please read the ``ghcid``documentation for installation and usage instructions.
+Please read the ``ghcid``documentation for installation and usage
+instructions. The [FAQ](https://github.com/ndmitchell/ghcid#faq) provides
+some useful tips.

level04/src/FirstApp/DB.hs

@@ -2,8 +2,8 @@
 {-# OPTIONS_GHC -fno-warn-unused-matches #-}
 module FirstApp.DB
   ( FirstAppDB (FirstAppDB)
-  , initDb
-  , closeDb
+  , initDB
+  , closeDB
   , addCommentToTopic
   , getComments
   , getTopics
@@ -35,19 +35,19 @@ import           FirstApp.Types                     (Comment, CommentText,
 data FirstAppDB = FirstAppDB
 
 -- Quick helper to pull the connection and close it down.
-closeDb
+closeDB
   :: FirstAppDB
   -> IO ()
-closeDb =
+closeDB =
   error "closeDb not implemented"
 
 -- Given a `FilePath` to our SQLite DB file, initialise the database and ensure
 -- our Table is there by running a query to create it, if it doesn't exist
 -- already.
-initDb
+initDB
   :: FilePath
   -> IO ( Either SQLiteResponse FirstAppDB )
-initDb fp =
+initDB fp =
   error "initDb not implemented"
   where
   -- Query has an `IsString` instance so string literals like this can be

level05/src/FirstApp/Conf/File.hs

@@ -70,18 +70,17 @@ decodeObj =
 
 -- | Update these tests when you've completed this function.
 --
--- | readObject
--- >>> readObject "badFileName.no"
+-- | readConfFile
+-- >>> readConfFile "badFileName.no"
 -- Left (undefined "badFileName.no: openBinaryFile: does not exist (No such file or directory)")
---
--- >>> readObject "test.json"
+-- >>> readConfFile "test.json"
 -- Right "{\n  \"foo\": 33\n}\n"
 --
-readObject
+readConfFile
   :: FilePath
   -> IO ( Either ConfigError ByteString )
-readObject =
-  error "readObject not implemented"
+readConfFile =
+  error "readConfFile not implemented"
 
 -- Construct the function that will take a ``FilePath``, read it in and attempt
 -- to decode it as a valid JSON object, using the ``aeson`` package. Then pull

level05/src/FirstApp/Main.hs

@@ -46,8 +46,8 @@ data StartUpError
 
 runApp :: IO ()
 runApp = do
-  -- Load up the configuration by providing a ``FilePath`` for the JSON config file.
-  cfgE <- error "configuration not implemented"
+  -- Load our configuration
+  cfgE <- prepareAppReqs
   -- Loading the configuration can fail, so we have to take that into account now.
   case cfgE of
     Left err   -> undefined

level05/src/FirstApp/Types.hs

@@ -110,6 +110,7 @@ fromDbComment dbc =
       <$> (mkTopic       $ dbCommentTopic dbc)
       <*> (mkCommentText $ dbCommentComment dbc)
       <*> (pure          $ dbCommentTime dbc)
+
 mkTopic
   :: Text
   -> Either Error Topic
@@ -200,7 +201,7 @@ confPortToWai
   :: Conf
   -> Int
 confPortToWai =
-  error "portToInt not implemented"
+  error "confPortToWai not implemented"
 
 -- Similar to when we were considering our application types, leave this empty
 -- for now and add to it as you go.

level06/src/FirstApp/Conf/File.hs

@@ -11,11 +11,11 @@ import           Data.Monoid                (Last (Last))
 
 import           Control.Exception          (try)
 
-import           Data.Aeson                 (FromJSON, Object)
+import           Data.Aeson                 (FromJSON, Object, (.:))
 
 import qualified Data.Aeson                 as Aeson
 
-import           FirstApp.Types             (ConfigError,
+import           FirstApp.Types             (ConfigError (JSONDecodeError,ConfigFileReadError),
                                              PartialConf (PartialConf))
 -- Doctest setup section
 -- $setup
@@ -47,8 +47,8 @@ fromJsonObjWithKey
   -> (a -> b)
   -> Object
   -> Last b
-fromJsonObjWithKey =
-  error "fromJsonObjWithKey not implemented"
+fromJsonObjWithKey k c o =
+  Last $ c <$> Aeson.parseMaybe (.: k) o
 
 -- |----
 -- | You will need to update these tests when you've completed the following functions!
@@ -66,22 +66,21 @@ decodeObj
   :: ByteString
   -> Either ConfigError Object
 decodeObj =
-  error "decodeObj not implemented"
+  first JSONDecodeError . Aeson.eitherDecode
 
 -- | Update these tests when you've completed this function.
 --
--- | readObject
--- >>> readObject "badFileName.no"
--- Left (undefined badFileName.no: openBinaryFile: does not exist (No such file or directory))
+-- | readConfFile
+-- >>> readConfFile "badFileName.no"
+-- Left (undefined "badFileName.no: openBinaryFile: does not exist (No such file or directory)")
+-- >>> readConfFile "test.json"
+-- Right "{\n  \"foo\": 33\n}\n"
 --
--- >>> readObject "test.json"
--- Right "{\"foo\":33}\n"
---
-readObject
+readConfFile
   :: FilePath
   -> IO ( Either ConfigError ByteString )
-readObject =
-  error "readObject not implemented"
+readConfFile fp =
+  first ConfigFileReadError <$> try (LBS.readFile fp)
 
 -- Construct the function that will take a ``FilePath``, read it in and attempt
 -- to decode it as a valid JSON object, using the ``aeson`` package. Then pull
@@ -90,5 +89,13 @@ readObject =
 parseJSONConfigFile
   :: FilePath
   -> IO ( Either ConfigError PartialConf )
-parseJSONConfigFile =
-  error "parseJSONConfigFile not implemented"
+parseJSONConfigFile fp =
+  fmap toPartialConf . ( decodeObj =<< ) <$> readObject fp
+  where
+    toPartialConf
+      :: Aeson.Object
+      -> PartialConf
+    toPartialConf cObj = PartialConf
+      ( fromJsonObjWithKey "port" Port cObj )
+      ( fromJsonObjWithKey "helloMsg" helloFromStr cObj )
+

level06/src/FirstApp/Types.hs

@@ -23,6 +23,8 @@ module FirstApp.Types
   , confPortToWai
   ) where
 
+import System.IO.Error (IOError)
+
 import           GHC.Generics                       (Generic)
 import           GHC.Word                           (Word16)
 
@@ -206,6 +208,8 @@ confPortToWai =
 data ConfigError
   = MissingPort
   | MissingDBFilePath
+  | JSONDecodeError String
+  | ConfigFileReadError IOError
   deriving Show
 
 -- Our application will be able to load configuration from both a file and

level07/src/FirstApp/Conf/File.hs

@@ -11,11 +11,11 @@ import           Data.Monoid                (Last (Last))
 
 import           Control.Exception          (try)
 
-import           Data.Aeson                 (FromJSON, Object)
+import           Data.Aeson                 (FromJSON, Object, (.:))
 
 import qualified Data.Aeson                 as Aeson
 
-import           FirstApp.Types             (ConfigError,
+import           FirstApp.Types             (ConfigError (JSONDecodeError,ConfigFileReadError),
                                              PartialConf (PartialConf))
 -- Doctest setup section
 -- $setup
@@ -47,8 +47,8 @@ fromJsonObjWithKey
   -> (a -> b)
   -> Object
   -> Last b
-fromJsonObjWithKey =
-  error "fromJsonObjWithKey not implemented"
+fromJsonObjWithKey k c o =
+  Last $ c <$> Aeson.parseMaybe (.: k) o
 
 -- |----
 -- | You will need to update these tests when you've completed the following functions!
@@ -66,22 +66,21 @@ decodeObj
   :: ByteString
   -> Either ConfigError Object
 decodeObj =
-  error "decodeObj not implemented"
+  first JSONDecodeError . Aeson.eitherDecode
 
 -- | Update these tests when you've completed this function.
 --
--- | readObject
--- >>> readObject "badFileName.no"
--- Left (undefined badFileName.no: openBinaryFile: does not exist (No such file or directory))
+-- | readConfFile
+-- >>> readConfFile "badFileName.no"
+-- Left (undefined "badFileName.no: openBinaryFile: does not exist (No such file or directory)")
+-- >>> readConfFile "test.json"
+-- Right "{\n  \"foo\": 33\n}\n"
 --
--- >>> readObject "test.json"
--- Right "{\"foo\":33}\n"
---
-readObject
+readConfFile
   :: FilePath
   -> IO ( Either ConfigError ByteString )
-readObject =
-  error "readObject not implemented"
+readConfFile fp =
+  first ConfigFileReadError <$> try (LBS.readFile fp)
 
 -- Construct the function that will take a ``FilePath``, read it in and attempt
 -- to decode it as a valid JSON object, using the ``aeson`` package. Then pull
@@ -90,5 +89,12 @@ readObject =
 parseJSONConfigFile
   :: FilePath
   -> IO ( Either ConfigError PartialConf )
-parseJSONConfigFile =
-  error "parseJSONConfigFile not implemented"
+parseJSONConfigFile fp =
+  fmap toPartialConf . ( decodeObj =<< ) <$> readObject fp
+  where
+    toPartialConf
+      :: Aeson.Object
+      -> PartialConf
+    toPartialConf cObj = PartialConf
+      ( fromJsonObjWithKey "port" Port cObj )
+      ( fromJsonObjWithKey "helloMsg" helloFromStr cObj )

level07/src/FirstApp/Types.hs

@@ -23,6 +23,8 @@ module FirstApp.Types
   , confPortToWai
   ) where
 
+import System.IO.Error (IOError)
+
 import           GHC.Generics                       (Generic)
 import           GHC.Word                           (Word16)
 
@@ -199,6 +201,8 @@ confPortToWai =
 data ConfigError
   = MissingPort
   | MissingDBFilePath
+  | JSONDecodeError String
+  | ConfigFileReadError IOError
   deriving Show
 
 -- Our application will be able to load configuration from both a file and