homework_7 - Полозков Марк

homeworks/homework_1/task_1/console-output.txt

@@ -0,0 +1,72 @@
+PS C:\Users\Y\IdeaProjects\naumen_scala_urfu_2023\naumen.scala.course.2023.spring> scala
+Welcome to Scala 2.12.10 (Java HotSpot(TM) 64-Bit Server VM, Java 19.0.1).
+Type in expressions for evaluation. Or try :help.
+
+scala> println("Ni hao")
+Ni hao
+
+scala> println("Hello Scala! This is Mark")
+Hello Scala! This is Mark
+
+scala> val name = Mark Polozkov
+<console>:11: error: not found: value Mark
+       val name = Mark Polozkov
+                  ^
+<console>:11: warning: postfix operator Poloz should be enabled
+by making the implicit value scala.language.postfixOps visible.
+This can be achieved by adding the import clause 'import scala.language.postfixOps'
+or by setting the compiler option -language:postfixOps.
+See the Scaladoc for value scala.language.postfixOps for a discussion
+why the feature should be explicitly enabled.
+       val name = Mark Polozkov
+                       ^
+
+scala> val name = "Mark Polozkov"
+name: String = Mark Polozkov
+
+scala> val small_turple = ("Hello","Hola","Guten morgen")
+small_turple: (String, String, String) = (Hello,Hola,Guten morgen)
+
+scala> val phrase = " Scala! This is "
+phrase: String = " Scala! This is "
+
+scala> println(small_turple(1) + phrase + name)
+<console>:15: error: (String, String, String) does not take parameters
+       println(small_turple(1) + phrase + name)
+                           ^
+
+scala> println(small_turple)
+(Hello,Hola,Guten morgen)
+
+scala> small_turple.getClass
+res4: Class[_ <: (String, String, String)] = class scala.Tuple3
+
+scala> small_turple(0)
+<console>:13: error: (String, String, String) does not take parameters
+       small_turple(0)
+                   ^
+
+scala> small_turple.0
+<console>:1: error: ';' expected but double literal found.
+       small_turple.0
+                   ^
+
+scala> small_turple[0]
+<console>:1: error: identifier expected but integer literal found.
+       small_turple[0]
+                    ^
+
+scala> small_turple._1
+res6: String = Hello
+
+
+scala> val new_seq = Seq("Hello","Hola","Guten morgen")
+new_seq: Seq[String] = List(Hello, Hola, Guten morgen)
+
+scala> for (elem <- new_seq) println(elem + phrase + name)
+Hello Scala! This is Mark Polozkov
+Hola Scala! This is Mark Polozkov
+Guten morgen Scala! This is Mark Polozkov
+
+
+scala>

homeworks/homework_1/task_2/scastie-url.txt

@@ -0,0 +1 @@
+https://scastie.scala-lang.org/aBFFrmeIT1e24FKS4rRy7Q

homeworks/homework_7/src/main/scala/MonadFunctor.scala

@@ -1,23 +1,24 @@
-
 trait Monad[F[_]] {
-
     def pure[A](a: A): F[A]
 
     def flatMap[A, B](fa: F[A])(f: A => F[B]): F[B]
 
     def map2[A, B, C](fa: F[A], fb: F[B])(f: (A, B) => C): F[C] = ???
+    def map2[A, B, C](fa: F[A], fb: F[B])(f: (A, B) => C): F[C] = flatMap(fa)(x => flatMap(fb)(y => pure(f(x, y))))
 
     def sequence[A](fas: List[F[A]]): F[List[A]] = ???
+    def sequence[A](fas: List[F[A]]): F[List[A]] = fas.foldRight(pure(List[A]()))((a, b) => map2(a, b)((c, d) => c :: d))
 
     def compose[A, B, C](f: A => F[B])(g: B => F[C]): A => F[C] = ???
+    def compose[A, B, C](f: A => F[B])(g: B => F[C]): A => F[C] = a => flatMap(f(a))(g)
 }
 
 trait Functor[F[_]] {
-    def map[A, B](a: F[A])(f: A => B): F[B]
-}
+@@ -18,6 +18,6 @@ trait Functor[F[_]] {
 
 object Functor {
     def functorFromMonad[F[_]](M: Monad[F]): Functor[F] = new Functor[F] {
         def map[A, B](a: F[A])(f: A => B): F[B] = ???
+        def map[A, B](a: F[A])(f: A => B): F[B] = M.flatMap(a)(b => M.pure(f(b)))
     }
 }