Prepare course 5

slides/Course03.hs

@@ -117,13 +117,6 @@ balance' = foldr (\op soFar -> toInt op + soFar) 0
   where
     toInt = \case Debit x -> -x; Credit x -> x
 
-class Functor f => Applicative f where
-  -- | Wraps a function in the functor
-  pure :: a -> f a
-
-  -- |
-  (<*>) :: f (a -> b) -> f a -> f b
-
 -- | @initials "Clément" "Hurlin"@ returns "CH"
 initials :: String -> String -> String
 initials firstname lastname =
@@ -147,43 +140,3 @@ mkEmail firstName lastName domain ext =
   let right = domain ++ "." ++ ext in
   left ++ "@" ++ right
 
-mkEmailSafe :: String -> String -> String -> Either String String
-mkEmailSafe user host ext =
-  checkUsername user
-  >>= \(username :: String) ->
-  checkExt ext
-  >>= \(extension :: String) ->
-  Right (username ++ "@" ++ host ++ "." ++ extension)
-  where
-    checkUsername :: String -> Either String String
-    checkUsername s =
-      if all isLower s
-        then Right s
-        else Left ("Username should be lowercase, but found: " ++ s)
-    checkExt :: String -> Either String String
-    checkExt "com" = Right "com"
-    checkExt "fr" = Right "fr"
-    checkExt s =
-      Left ("Unexpected extension: "
-              ++ show s
-              ++ ". Expected one of: [\"com\", \"fr\"]")
-
-mkEmailSafe' :: String -> String -> String -> Either String String
-mkEmailSafe' user host ext = do
-  username <- checkUsername user
-  extension <- checkExt ext
-  pure (username ++ "@" ++ host ++ "." ++ extension)
-  where
-    checkUsername :: String -> Either String String
-    checkUsername s =
-      if all isLower s
-        then Right s
-        else Left ("Username should be lowercase, but found: " ++ s)
-    checkExt :: String -> Either String String
-    checkExt "com" = Right "com"
-    checkExt "fr" = Right "fr"
-    checkExt s =
-      Left ("Unexpected extension: "
-              ++ show s
-              ++ ". Expected one of: [\"com\", \"fr\"]")
-

slides/Course05.hs

@@ -1,6 +1,33 @@
 module Course05 where
 
 import Control.Monad.IO.Class
+import Data.Char
 import Data.Word
 import Prelude hiding ((==), Bounded, Enum, Eq, Ordering, Show)
 
+mkEmailSafe :: String -> String -> String -> Either String String
+mkEmailSafe user host ext =
+  checkUsername user
+  >>= \(username :: String) ->
+  checkExt ext
+  >>= \(extension :: String) ->
+  Right (username ++ "@" ++ host ++ "." ++ extension)
+
+checkUsername :: String -> Either String String
+checkUsername s | all isLower s = Right s
+                | otherwise     = Left ("Username should be lowercase, but found: " ++ s)
+checkExt :: String -> Either String String
+checkExt =
+  \case
+    "com" -> Right "com"
+    "fr"  -> Right "fr"
+    s     -> Left ("Unexpected extension: "
+                     ++ show s
+                     ++ ". Expected one of: [\"com\", \"fr\"]")
+
+mkEmailSafe' :: String -> String -> String -> Either String String
+mkEmailSafe' user host ext = do
+  username <- checkUsername user
+  extension <- checkExt ext
+  pure (username ++ "@" ++ host ++ "." ++ extension)
+

slides/course-03.md

@@ -563,105 +563,6 @@ Its syntax is: `let varName = expression in expression`
 - What is the type of `mkEmail`?
   - How does inference work?
 
----
-
-# More composition
-
-```bash
-> import Data.Functor
-> :type (<&>)
-(<&>) :: Functor f => f a -> (a -> b) -> f b
-> :type fmap
-fmap :: Functor f => (a -> b) -> f a -> f b
-```
-
-- Given an element of type `a` wrapped in something (`f`), and a function from `a` to `b`, apply the function inside the wrapping.
-
-- What can be `f`?
-
-???
-
-```bash
-> import Data.List.Extra
-> :type upper
-upper :: String -> String
-> applyUpper = fmap upper
-> applyUpper (Just "foo")
-> applyUpper (Right "foo" :: Either Int String)
-```
-
-???
-
-If done at this point and time remains:
-
-- Explain `foldr`
-- Explain things defined in terms of `foldr`:
-  - `sum`
-  - `and :: [Bool] -> Bool`
-  - `any :: (a -> Bool) -> [a] -> Bool`
-
----
-
-# More composition: monads
-
-```bash
-> :type (>>=)
-(>>=) :: Monad m => m a -> (a -> m b) -> m b
-```
-
-```hs
-mkEmailSafe :: String -> String -> String -> Either String String
-mkEmailSafe user host ext =
-  checkUsername user
-  >>= \(username :: String) ->
-  checkExt ext
-  >>= \(extension :: String) ->
-  Right (username ++ "@" ++ host ++ "." ++ extension)
-  where
-    checkUsername :: String -> Either String String
-    checkUsername s =
-      if all isLower s
-        then Right s
-        else Left ("Username should be lowercase, but found: " ++ s)
-    checkExt :: String -> Either String String
-    checkExt "com" = Right "com"
-    checkExt "fr" = Right "fr"
-    checkExt s =
-      Left ("Unexpected extension: "
-              ++ show s
-              ++ ". Expected one of: [\"com\", \"fr\"]")
-```
-
----
-
-# User friendly monads: the `do` notation
-
-```bash
-> :type (>>=)
-(>>=) :: Monad m => m a -> (a -> m b) -> m b
-```
-
-```hs
-mkEmailSafe' :: String -> String -> String -> Either String String
-mkEmailSafe' user host ext = do
-  username <- checkUsername user
-  extension <- checkExt ext
-  pure (username ++ "@" ++ host ++ "." ++ extension)
-  where
-    checkUsername :: String -> Either String String
-    checkUsername s =
-      if all isLower s
-        then Right s
-        else Left ("Username should be lowercase, but found: " ++ s)
-    checkExt :: String -> Either String String
-    checkExt "com" = Right "com"
-    checkExt "fr" = Right "fr"
-    checkExt s =
-      Left ("Unexpected extension: "
-              ++ show s
-              ++ ". Expected one of: [\"com\", \"fr\"]")
-```
-
 <!-- Machinery for making the snippets valid, not shown, only
      used by exdown (see check.sh).
 

slides/course-04.md

@@ -369,7 +369,25 @@ class Functor f where
   fmap :: (a -> b) -> f a -> f b
 ```
 
-- Give instances:
+```bash
+> import Data.List.Extra
+> :type upper
+upper :: String -> String
+> applyUpper = fmap upper
+> :type applyUpper
+applyUpper :: Functor f => f String -> f String
+```
+
+--
+
+```bash
+> applyUpper (Just "foo")
+> applyUpper (Right "foo" :: Either Int String)
+```
+
+--
+
+- Instances we've seen before:
   - `Maybe a`
   - `[a]`
 

slides/course-05.html

@@ -0,0 +1,31 @@
+<!DOCTYPE html>
+<html>
+  <head>
+    <title>Mastering the Type System</title>
+    <meta charset="utf-8">
+    <style>
+      @import url(https://fonts.googleapis.com/css?family=Yanone+Kaffeesatz);
+      @import url(https://fonts.googleapis.com/css?family=Droid+Serif:400,700,400italic);
+      @import url(https://fonts.googleapis.com/css?family=Ubuntu+Mono:400,700,400italic);
+
+      body { font-family: 'Droid Serif'; }
+      h1, h2, h3 {
+        font-family: 'Yanone Kaffeesatz';
+        font-weight: normal;
+      }
+      .remark-code, .remark-inline-code { font-family: 'Ubuntu Mono'; }
+      .remark-inline-code { background-color: #F0F0F0; }
+    </style>
+  </head>
+  <body>
+    <!-- See https://github.com/gnab/remark/wiki for guidance -->
+    <script src="https://remarkjs.com/downloads/remark-latest.min.js">
+    </script>
+    <script>
+var slideshow = remark.create({
+  sourceUrl: 'course-05.md'
+});
+    </script>
+  </body>
+</html>
+

slides/course-05.md

@@ -19,6 +19,7 @@ Clément Hurlin
 module Course05 where
 
 import Control.Monad.IO.Class
+import Data.Char
 import Data.Word
 import Prelude hiding ((==), Bounded, Enum, Eq, Ordering, Show)
 ```
@@ -39,7 +40,7 @@ class Course05 {
 In this course:
 
 <center>
-  Advanced Type System
+  Mastering the Type System
 </center>
 
 <br/>
@@ -48,9 +49,48 @@ In this course:
 
 # Monads
 
+```bash
+> :type (>>=)
+(>>=) :: Monad m => m a -> (a -> m b) -> m b
+```
+
+```hs
+mkEmailSafe :: String -> String -> String -> Either String String
+mkEmailSafe user host ext =
+  checkUsername user
+  >>= \(username :: String) ->
+  checkExt ext
+  >>= \(extension :: String) ->
+  Right (username ++ "@" ++ host ++ "." ++ extension)
+
+checkUsername :: String -> Either String String
+checkUsername s | all isLower s = Right s
+                | otherwise     = Left ("Username should be lowercase, but found: " ++ s)
+checkExt :: String -> Either String String
+checkExt =
+  \case
+    "com" -> Right "com"
+    "fr"  -> Right "fr"
+    s     -> Left ("Unexpected extension: "
+                     ++ show s
+                     ++ ". Expected one of: [\"com\", \"fr\"]")
+```
 ---
 
-# Type Applications
+# User friendly monads: the `do` notation
+
+```bash
+> :type (>>=)
+(>>=) :: Monad m => m a -> (a -> m b) -> m b
+```
+
+```hs
+mkEmailSafe' :: String -> String -> String -> Either String String
+mkEmailSafe' user host ext = do
+  username <- checkUsername user
+  extension <- checkExt ext
+  pure (username ++ "@" ++ host ++ "." ++ extension)
+```
 
 ---
 

tn-fp-course.cabal

@@ -60,6 +60,7 @@ library slides
                       Course02
                       Course03
                       Course04
+                      Course05
 
 executable TP1.hs
     import:           common-all