From d8b22157c56f5743b8446abee6a03e04ec196394 Mon Sep 17 00:00:00 2001
From: LordBaryhobal <lordbaryhobal@gmail.com>
Date: Tue, 15 Apr 2025 15:07:26 +0200
Subject: [PATCH] added lesson 7

---
 README.md                     | 28 ++++++++++++++++++++--------
 src/Lesson7/Daltons.sc        | 12 ++++++++++++
 src/Lesson7/LazyEvaluation.sc |  6 ++++++
 src/Lesson7/LazyList.sc       | 11 +++++++++++
 src/Lesson7/LoggingFactory.sc | 16 ++++++++++++++++
 src/Lesson7/Variance.sc       | 25 +++++++++++++++++++++++++
 src/MidTermPrep1/Exercices.sc |  8 ++++++++
 7 files changed, 98 insertions(+), 8 deletions(-)
 create mode 100644 src/Lesson7/Daltons.sc
 create mode 100644 src/Lesson7/LazyEvaluation.sc
 create mode 100644 src/Lesson7/LazyList.sc
 create mode 100644 src/Lesson7/LoggingFactory.sc
 create mode 100644 src/Lesson7/Variance.sc
 create mode 100644 src/MidTermPrep1/Exercices.sc

diff --git a/README.md b/README.md
index e5201e4..7331c4d 100644
--- a/README.md
+++ b/README.md
@@ -57,13 +57,6 @@
 [Files](src/Lesson5)
 - Lists
 - High order functions
-- 
-### Lesson 6 - Tuples and comprehensions
-[Files](src/Lesson6)
-- Tuples
-- For-comprehension
-- Yield
-- Flatmap
 
 ### Midterm preparation
 [Files](src/MidTermPrep1)
@@ -71,6 +64,20 @@
 ### Midterm
 [Files](src/MidTerm1)
 
+### Lesson 6 - Tuples and comprehensions
+[Files](src/Lesson6)
+- Tuples
+- For-comprehension
+- Yield
+- Flatmap
+
+### Lesson 7 - Advanced typing and infinite lists
+[Files](src/Lesson7)
+- Types
+- Bounds
+- Traits
+- Variance, covariance and contra-variance
+- Infinite sequences
 
 ## Assignments
 
@@ -105,4 +112,9 @@
 - Lists
 - Map
 - Fold
-- Zip
\ No newline at end of file
+- Zip
+
+### Assignment 6 - Sequence comprehension and tuples
+[Files](src/Assignment6)
+- Tuples
+- `for` comprehension
\ No newline at end of file
diff --git a/src/Lesson7/Daltons.sc b/src/Lesson7/Daltons.sc
new file mode 100644
index 0000000..1d81183
--- /dev/null
+++ b/src/Lesson7/Daltons.sc
@@ -0,0 +1,12 @@
+case class Dalton(n: Int) extends Ordered[Dalton] {
+  //override def compare(that: Dalton): Int = this.n compare that.n
+  override def compare(that: Dalton): Int = this.n - that.n
+}
+
+val a = Dalton(2); val b = Dalton(3); val c = Dalton(2)
+
+a < b
+a > b
+a == b
+a == c
+a >= c
\ No newline at end of file
diff --git a/src/Lesson7/LazyEvaluation.sc b/src/Lesson7/LazyEvaluation.sc
new file mode 100644
index 0000000..7b5deb2
--- /dev/null
+++ b/src/Lesson7/LazyEvaluation.sc
@@ -0,0 +1,6 @@
+val expr = {
+  val x = {print("x"); 1}
+  lazy val y = {print("y"); 2}
+  def z = {print("z"); 3}
+  z + y + x + z + y + x
+}
\ No newline at end of file
diff --git a/src/Lesson7/LazyList.sc b/src/Lesson7/LazyList.sc
new file mode 100644
index 0000000..9bc7e9d
--- /dev/null
+++ b/src/Lesson7/LazyList.sc
@@ -0,0 +1,11 @@
+def range(low: Int, high: Int): LazyList[Int] = {
+  println(s"Calling range with low=$low / high=$high")
+  if (low >= high) LazyList.empty[Int]
+  else low #:: range(low + 1, high)
+}
+
+range(1, 10)(0)
+
+range(1, 10) map (x => x + 1)
+
+(range(1, 10) map (x => x + 1)).toList
diff --git a/src/Lesson7/LoggingFactory.sc b/src/Lesson7/LoggingFactory.sc
new file mode 100644
index 0000000..31fd85a
--- /dev/null
+++ b/src/Lesson7/LoggingFactory.sc
@@ -0,0 +1,16 @@
+trait Logged {
+  def log(msg: String)
+}
+
+trait ConsoleLogger extends Logged {
+  override def log(msg: String) = println("[LOG] " + msg)
+}
+
+abstract class Person(name: String)
+
+class Customer(n: String) extends Person(n) with Logged {
+  log(s"Person $n created")
+}
+
+val a = new Customer("Patrick Jane") with ConsoleLogger
+
diff --git a/src/Lesson7/Variance.sc b/src/Lesson7/Variance.sc
new file mode 100644
index 0000000..9da3a87
--- /dev/null
+++ b/src/Lesson7/Variance.sc
@@ -0,0 +1,25 @@
+class Animal(val name: String, val kind: String)
+class Cat(name: String) extends Animal(name, "Cat")
+class Dog(name: String) extends Animal(name, "Dog")
+
+val anim1: Animal = new Animal("Booboo", "Baboon")
+val cat1 = new Cat("Miaou")
+
+// Standard polymorphism
+val anim2: Animal = cat1
+
+val dog1: Dog = new Dog("Choucroute")
+val anim3: Animal = dog1
+
+class Container[+A](val elems: List[A]) {
+  def get(i: Int): A = elems(i)
+  def put[B >: A](elem: B) = new Container(elem::elems)
+}
+
+val animalCollection = new Container[Animal](Nil).put(anim1)
+
+val catCollection = new Container[Cat](Nil).put(cat1).put(new Cat("Garfield"))
+
+animalCollection.put(cat1)
+
+val animalCollection2: Container[Animal] = catCollection
\ No newline at end of file
diff --git a/src/MidTermPrep1/Exercices.sc b/src/MidTermPrep1/Exercices.sc
new file mode 100644
index 0000000..133ebf4
--- /dev/null
+++ b/src/MidTermPrep1/Exercices.sc
@@ -0,0 +1,8 @@
+def compress[T](list: List[T]): List[T] = {
+  list.foldRight(List.empty[T])((elmt: T, res: List[T]) => res match {
+    case head::_ if head == elmt => res
+    case _ => elmt::res
+  })
+}
+
+compress(List('a', 'a', 'a', 'a', 'b', 'c', 'c', 'a', 'a', 'd', 'e', 'e', 'e', 'e'))
\ No newline at end of file