aoiroaoino · September 16, 2019 06:28 · Sep 16, 2019 · Sep 16, 2019 · Sep 15, 2019 · Sep 15, 2019
diff --git a/a.md b/a.md
@@ -24,9 +24,4 @@
 
 - scalaz.IndexedContsT
   - https://github.com/scalaz/scalaz/blob/v7.2.28/core/src/main/scala/scalaz/IndexedContsT.scala
-
-
-### 発表当日の質問
-
-<img width="1307" alt="スクリーンショット 2019-09-16 15 17 36" src="https://user-images.githubusercontent.com/2589034/64937483-5e941300-d895-11e9-8870-7ae646f8fbef.png">
-
+
diff --git a/b.md b/b.md
@@ -0,0 +1,22 @@
+### 発表当日の質問
+
+<img width="1307" alt="スクリーンショット 2019-09-16 15 17 36" src="https://user-images.githubusercontent.com/2589034/64937483-5e941300-d895-11e9-8870-7ae646f8fbef.png">
+
+#### Q&A 1
+
+Q:
+ここでの「継続」と「関数」の違いは何でしょうか？「継続 = その後に計算される計算/処理」だとして、
+Scalaにおいては関数が「継続」を表現するのにちょうど良いので、関数を使って「継続渡し」を説明している、という感じでしょうか？
+A:
+
+#### Q&A 2
+
+Q:
+for式で使いたいだけであればモナドにする必要はないと思いますが、モナドにしておく理由はありますか？
+A:
+
+#### Q&A 3
+Q:
+継続を見て「これはモナドかも？」という直感が働くのはどういった点ですか？
+A:
+
diff --git a/a.md b/a.md
@@ -24,3 +24,9 @@
 
 - scalaz.IndexedContsT
   - https://github.com/scalaz/scalaz/blob/v7.2.28/core/src/main/scala/scalaz/IndexedContsT.scala
+
+
+### 発表当日の質問
+
+<img width="1307" alt="スクリーンショット 2019-09-16 15 17 36" src="https://user-images.githubusercontent.com/2589034/64937483-5e941300-d895-11e9-8870-7ae646f8fbef.png">
+
diff --git a/a.md b/a.md
@@ -5,7 +5,7 @@
 
 ### 補足とか
 
-- 限定継続です。触れてなくて大丈夫...?
+- 限定継続...
 - エラーハンドリングの実用例みたいなもの
   - https://github.com/aoiroaoino/monoton/blob/a4f326bfa0c/core/src/main/scala/monoton/server/Handler.scala
 

diff --git a/a.md b/a.md
@@ -1,15 +1,15 @@
-# 検証環境とか
+### 検証環境とか
 
 - Scala 2.13.0 の REPL
 - ScalaCheck 1.14.0
 
-# 補足とか
+### 補足とか
 
 - 限定継続です。触れてなくて大丈夫...?
 - エラーハンドリングの実用例みたいなもの
   - https://github.com/aoiroaoino/monoton/blob/a4f326bfa0c/core/src/main/scala/monoton/server/Handler.scala
 
-# 参考資料
+### 参考資料
 
 （敬称略）
 

diff --git a/a.md b/a.md
@@ -0,0 +1,26 @@
+# 検証環境とか
+
+- Scala 2.13.0 の REPL
+- ScalaCheck 1.14.0
+
+# 補足とか
+
+- 限定継続です。触れてなくて大丈夫...?
+- エラーハンドリングの実用例みたいなもの
+  - https://github.com/aoiroaoino/monoton/blob/a4f326bfa0c/core/src/main/scala/monoton/server/Handler.scala
+
+# 参考資料
+
+（敬称略）
+
+- shift/reset プログラミング入門 - 浅井 健一
+  - http://pllab.is.ocha.ac.jp/~asai/cw2011tutorial/main-j.pdf
+
+- モナドから始めない継続入門 - @cloudear8
+  - https://blog.7nobo.me/2018/01/14/01-haskell-continuation.html
+
+- Loan パターンのネストは継続モナドでシュッと解決できるよという話 - @jwhaco
+  - https://qiita.com/jwhaco/items/224113324fd454b8ca77
+
+- scalaz.IndexedContsT
+  - https://github.com/scalaz/scalaz/blob/v7.2.28/core/src/main/scala/scalaz/IndexedContsT.scala
diff --git a/practice_12_resource.scala b/practice_12_resource.scala
@@ -31,20 +31,20 @@ res140: List[String] = List(Hello, 1, Hello, 2, Hello, 3)
 // ===
 
 // close() 実行時に println する独自 Releasable を定義
-def releasable(n: String): Using.Releasable[AutoCloseable] =
+def r(n: String): Using.Releasable[AutoCloseable] =
   _.close().tap(_ => println(s"call close() for $n"))
 
 // Releasable を明示的に渡して実行
 val prog: Cont[List[String], List[String]] = for {
-  a <- resource(new BufferedReader(new FileReader("/tmp/file1.txt")))(releasable("file1"))
-  b <- resource(new BufferedReader(new FileReader("/tmp/file2.txt")))(releasable("file2"))
-  c <- resource(new BufferedReader(new FileReader("/tmp/file3.txt")))(releasable("file3"))
+  a <- resource(new BufferedReader(new FileReader("/tmp/file1.txt")))(r("f1"))
+  b <- resource(new BufferedReader(new FileReader("/tmp/file2.txt")))(r("f2"))
+  c <- resource(new BufferedReader(new FileReader("/tmp/file3.txt")))(r("f3"))
 } yield {
   (lines(a) ++ lines(b) ++ lines(c)).toList
 }
 
 scala> prog.run(identity)
-call close() for file3
-call close() for file2
-call close() for file1
-res143: List[String] = List(Hello, 1, Hello, 2, Hello, 3)
+call close() for f3
+call close() for f2
+call close() for f1
+res145: List[String] = List(Hello, 1, Hello, 2, Hello, 3)
diff --git a/practice_12_resource.scala b/practice_12_resource.scala
@@ -1,40 +1,50 @@
 // ===
 
+def using[A <: AutoCloseable, B](a: => A, n: String)(f: A => B): B =
+  try f(a) finally { a.close(); println(s"close: $n") }
+
 // Scala 2.13.0 より scala.util.Using が入った
 //話を簡略化するため、例外が投げられる resource を使用
 def resource[R, A](resource: R)(body: (R) => A)(implicit releasable: Releasable[R]): A
 
-// 
-
+// 継続モナドでラップ
 def resource[R, A](a: => A)(implicit releasable: Releasable[A]): Cont[R, A] =
   Cont(ar => Using.resource(a)(ar))
 
 // ===
 
-// Using.Magaer 
+def lines(reader: BufferedReader): Iterator[String] =
+  Iterator.unfold(())(_ => Option(reader.readLine()).map(_ -> ()))
+
+// Using.Magaer を使わず、しかも for 式で合成できる
 val prog: Cont[List[String], List[String]] = for {
-  _ <- Cont.pure[List[String], Unit](())
-  a <- resource(new BufferedReader(new FileReader("/tmp/file1.txt")))(releasable("file1"))
-  b <- resource(new BufferedReader(new FileReader("/tmp/file2.txt")))(releasable("file2"))
-  c <- resource(new BufferedReader(new FileReader("/tmp/file3.txt")))(releasable("file3"))
+  a <- resource(new BufferedReader(new FileReader("/tmp/file1.txt")))
+  b <- resource(new BufferedReader(new FileReader("/tmp/file2.txt")))
+  c <- resource(new BufferedReader(new FileReader("/tmp/file3.txt")))
 } yield {
- def lines(reader: BufferedReader): Iterator[String] =
-    Iterator.unfold(())(_ => Option(reader.readLine()).map(_ -> ()))
   (lines(a) ++ lines(b) ++ lines(c)).toList
 }
 
-def releasable(n: String): Using.Releasable[AutoCloseable] =
-  new Using.Releasable[AutoCloseable] {
-    def release(resource: AutoCloseable): Unit = {
-      println(s"close() call for $n")
-      resource.close()
-    }
-  }
+scala> prog.run(identity)
+res140: List[String] = List(Hello, 1, Hello, 2, Hello, 3)
 
-prog.run(identity)
+// ===
 
+// close() 実行時に println する独自 Releasable を定義
+def releasable(n: String): Using.Releasable[AutoCloseable] =
+  _.close().tap(_ => println(s"call close() for $n"))
 
-// ===
+// Releasable を明示的に渡して実行
+val prog: Cont[List[String], List[String]] = for {
+  a <- resource(new BufferedReader(new FileReader("/tmp/file1.txt")))(releasable("file1"))
+  b <- resource(new BufferedReader(new FileReader("/tmp/file2.txt")))(releasable("file2"))
+  c <- resource(new BufferedReader(new FileReader("/tmp/file3.txt")))(releasable("file3"))
+} yield {
+  (lines(a) ++ lines(b) ++ lines(c)).toList
+}
 
-def using[A <: AutoCloseable, B](a: => A, n: String)(f: A => B): B =
-  try f(a) finally { a.close(); println(s"close: $n") }
+scala> prog.run(identity)
+call close() for file3
+call close() for file2
+call close() for file1
+res143: List[String] = List(Hello, 1, Hello, 2, Hello, 3)
diff --git a/practice_12_resource.scala b/practice_12_resource.scala
@@ -1,8 +1,40 @@
 // ===
 
-// Scala 2.13.0 より Using が入った
+// Scala 2.13.0 より scala.util.Using が入った
+//話を簡略化するため、例外が投げられる resource を使用
+def resource[R, A](resource: R)(body: (R) => A)(implicit releasable: Releasable[R]): A
 
-def resource[R, A](a: => A)(implicit F: Releasable[A]): Cont[R, A] =
+// 
+
+def resource[R, A](a: => A)(implicit releasable: Releasable[A]): Cont[R, A] =
   Cont(ar => Using.resource(a)(ar))
 
-// ===
+// ===
+
+// Using.Magaer 
+val prog: Cont[List[String], List[String]] = for {
+  _ <- Cont.pure[List[String], Unit](())
+  a <- resource(new BufferedReader(new FileReader("/tmp/file1.txt")))(releasable("file1"))
+  b <- resource(new BufferedReader(new FileReader("/tmp/file2.txt")))(releasable("file2"))
+  c <- resource(new BufferedReader(new FileReader("/tmp/file3.txt")))(releasable("file3"))
+} yield {
+ def lines(reader: BufferedReader): Iterator[String] =
+    Iterator.unfold(())(_ => Option(reader.readLine()).map(_ -> ()))
+  (lines(a) ++ lines(b) ++ lines(c)).toList
+}
+
+def releasable(n: String): Using.Releasable[AutoCloseable] =
+  new Using.Releasable[AutoCloseable] {
+    def release(resource: AutoCloseable): Unit = {
+      println(s"close() call for $n")
+      resource.close()
+    }
+  }
+
+prog.run(identity)
+
+
+// ===
+
+def using[A <: AutoCloseable, B](a: => A, n: String)(f: A => B): B =
+  try f(a) finally { a.close(); println(s"close: $n") }
diff --git a/practice_13_attention.scala b/practice_13_attention.scala
@@ -54,6 +54,7 @@ val prog: Cont[Unit, Unit] =
     _ <- insert("some data")
   } yield ()
 
+// めでたく二回実行されてしまいました
 scala> prog.run(identity)
 insert data to database
 insert data to database
diff --git a/practice_13_attention.scala b/practice_13_attention.scala
@@ -35,3 +35,25 @@ val prog: Cont[Result, List[User]] =
 
 scala> prog.run(_.mkString(", "))
 res133: Result = query execution error
+
+
+// ===
+
+// 後続の処理をなんとなく二回実行するやつ
+def twice: Cont[Unit, Unit] = Cont { ar => ar(()); ar(()) }
+
+// 絶対に一回しか実行して欲しくない DB への書き込み
+def insert(s: String): Cont[Unit, Unit] = Cont { ar =>
+  println("insert data to database")
+  ar(())
+}
+
+val prog: Cont[Unit, Unit] =
+  for {
+    _ <- twice
+    _ <- insert("some data")
+  } yield ()
+
+scala> prog.run(identity)
+insert data to database
+insert data to database
diff --git a/practice_13_attention.scala b/practice_13_attention.scala
@@ -25,7 +25,7 @@ res132: Result = [foo], [bar]
 
 // ===
 
-// 継続の最後の方で例外が投げられた場合
+// 継続の深いところで例外が投げられた場合
 val prog: Cont[Result, List[User]] =
   for {
     users <- findAll()

diff --git a/practice_13_attention.scala b/practice_13_attention.scala
@@ -13,6 +13,7 @@ def findAll[R](): Cont[Result, List[User]] = Cont { ar =>
 
 // ===
 
+// 全て成功する場合
 val prog: Cont[Result, List[User]] =
   for {
     users <- findAll()
@@ -24,11 +25,12 @@ res132: Result = [foo], [bar]
 
 // ===
 
+// 継続の最後の方で例外が投げられた場合
 val prog: Cont[Result, List[User]] =
   for {
     users <- findAll()
     names <- Cont.pure(users.map(n => s"[$n]"))
-    _ = 1 / 0
+    _ = 1 / 0 // java.lang.ArithmeticException: / by zero
   } yield names
 
 scala> prog.run(_.mkString(", "))

diff --git a/practice_12_resource.scala b/practice_12_resource.scala
@@ -1 +1,8 @@
-w
+// ===
+
+// Scala 2.13.0 より Using が入った
+
+def resource[R, A](a: => A)(implicit F: Releasable[A]): Cont[R, A] =
+  Cont(ar => Using.resource(a)(ar))
+
+// ===
diff --git a/practice_13_attention.scala b/practice_13_attention.scala
@@ -0,0 +1,35 @@
+// ===
+
+type User = String
+type Result = String
+
+def findAll[R](): Cont[Result, List[User]] = Cont { ar =>
+  try {
+    ar(List("foo", "bar")) // DB への問い合わせは成功したとする
+  } catch {
+    case _: Throwable => "query execution error"
+  }
+}
+
+// ===
+
+val prog: Cont[Result, List[User]] =
+  for {
+    users <- findAll()
+    names <- Cont.pure(users.map(n => s"[$n]"))
+  } yield names
+
+scala> prog.run(_.mkString(", "))
+res132: Result = [foo], [bar]
+
+// ===
+
+val prog: Cont[Result, List[User]] =
+  for {
+    users <- findAll()
+    names <- Cont.pure(users.map(n => s"[$n]"))
+    _ = 1 / 0
+  } yield names
+
+scala> prog.run(_.mkString(", "))
+res133: Result = query execution error
diff --git a/tips_11_monad_in_scala b/tips_11_monad_in_scala
@@ -1 +0,0 @@
-w

diff --git a/tips_11_monad_in_scala.scala b/tips_11_monad_in_scala.scala
@@ -1 +0,0 @@
-w

diff --git a/intro_22_cont_monad_law.scala b/intro_22_cont_monad_law.scala
@@ -48,10 +48,8 @@ class ContMonadSpec extends Properties("Monad[Cont[R, ?]]") {
 // ===
 
 sbt:check_cont_monad_law> test
-[info] Compiling 1 Scala source to /Users/aoiroaoino/work/check_cont_monad_law/target/scala-2.13/test-classes ...
-[info] Done compiling.
-[info] + Monad[Cont[R, ?]].leftIdentity: OK, passed 100 tests.
 [info] + Monad[Cont[R, ?]].rightIdentity: OK, passed 100 tests.
+[info] + Monad[Cont[R, ?]].leftIdentity: OK, passed 100 tests.
 [info] + Monad[Cont[R, ?]].associativity: OK, passed 100 tests.
 [info] Passed: Total 3, Failed 0, Errors 0, Passed 3
-[success] Total time: 1 s, completed 2019/09/15 19:42:15
+[success] Total time: 1 s, completed 2019/09/15 19:49:36
diff --git a/intro_22_cont_monad_law.scala b/intro_22_cont_monad_law.scala
@@ -29,29 +29,29 @@ object Cont {
 
 class ContMonadSpec extends Properties("Monad[Cont[R, ?]]") {
 
-  def add[R](i: Int, j: Int): Cont[Int, Int] = Cont(_(i + j))
-  def show[R](i: Int): Cont[String, String] = Cont(_(s"num: $i"))
+  def inc(i: Int): Cont[Int, Int] = Cont(_(i + 1))
+  def add_![R](s: String): Cont[String, String] = Cont(_(s + "!"))
+  def add_?[R](s: String): Cont[String, String] = Cont(_(s + "?"))
 
-  def exclamation[R](s: String): Cont[String, String] = Cont(_(s + "!"))
-  def question[R](s: String): Cont[String, String] = Cont(_(s + "?"))
-
-  property("rightIdentity") = Prop.forAll { (i: Int, j: Int) =>
-    add(i, j).flatMap(Cont.pure).run(identity) == add(i, j).run(identity)
+  property("rightIdentity") = Prop.forAll { i: Int =>
+    inc(i).flatMap(Cont.pure).run(identity) == inc(i).run(identity)
   }
   property("leftIdentity") = Prop.forAll { i: Int =>
-    Cont.pure[String, Int](i).flatMap(show).run(identity) == show(i).run(identity)
+    Cont.pure[Int, Int](i).flatMap(inc).run(identity) == inc(i).run(identity)
   }
   property("associativity") = Prop.forAll { s: String =>
-    Cont.pure(s).flatMap(exclamation).flatMap(question).run(identity) ==
-      Cont.pure(s).flatMap(a => exclamation(a).flatMap(question)).run(identity)
+    Cont.pure(s).flatMap(add_!).flatMap(add_?).run(identity) ==
+      Cont.pure(s).flatMap(a => add_!(a).flatMap(add_?)).run(identity)
   }
 }
 
 // ===
 
 sbt:check_cont_monad_law> test
+[info] Compiling 1 Scala source to /Users/aoiroaoino/work/check_cont_monad_law/target/scala-2.13/test-classes ...
+[info] Done compiling.
 [info] + Monad[Cont[R, ?]].leftIdentity: OK, passed 100 tests.
 [info] + Monad[Cont[R, ?]].rightIdentity: OK, passed 100 tests.
 [info] + Monad[Cont[R, ?]].associativity: OK, passed 100 tests.
 [info] Passed: Total 3, Failed 0, Errors 0, Passed 3
-[success] Total time: 0 s, completed 2019/09/15 19:34:12
+[success] Total time: 1 s, completed 2019/09/15 19:42:15
diff --git a/intro_22_cont_monad_law.scala b/intro_22_cont_monad_law.scala
@@ -1 +1,57 @@
-wip
+// ===
+sbt.version=1.2.8
+
+ThisBuild / scalaVersion     := "2.13.0"
+ThisBuild / version          := "0.1.0-SNAPSHOT"
+ThisBuild / organization     := "com.example"
+ThisBuild / organizationName := "example"
+
+lazy val root = (project in file("."))
+  .settings(
+    name := "check_cont_monad_law",
+    libraryDependencies += "org.scalacheck" %% "scalacheck" % "1.14.0" % Test
+  )
+
+// ===
+
+package example
+
+import org.scalacheck.{Prop, Properties}
+
+final case class Cont[R, A](run: (A => R) => R) {
+  def map[B](f: A => B): Cont[R, B] = Cont(br => run(f andThen br))
+  def flatMap[B](f: A => Cont[R, B]): Cont[R, B] =
+    Cont(br => run(f(_).run(br)))
+}
+object Cont {
+  def pure[R, A](a: A): Cont[R, A] = Cont(_(a))
+}
+
+class ContMonadSpec extends Properties("Monad[Cont[R, ?]]") {
+
+  def add[R](i: Int, j: Int): Cont[Int, Int] = Cont(_(i + j))
+  def show[R](i: Int): Cont[String, String] = Cont(_(s"num: $i"))
+
+  def exclamation[R](s: String): Cont[String, String] = Cont(_(s + "!"))
+  def question[R](s: String): Cont[String, String] = Cont(_(s + "?"))
+
+  property("rightIdentity") = Prop.forAll { (i: Int, j: Int) =>
+    add(i, j).flatMap(Cont.pure).run(identity) == add(i, j).run(identity)
+  }
+  property("leftIdentity") = Prop.forAll { i: Int =>
+    Cont.pure[String, Int](i).flatMap(show).run(identity) == show(i).run(identity)
+  }
+  property("associativity") = Prop.forAll { s: String =>
+    Cont.pure(s).flatMap(exclamation).flatMap(question).run(identity) ==
+      Cont.pure(s).flatMap(a => exclamation(a).flatMap(question)).run(identity)
+  }
+}
+
+// ===
+
+sbt:check_cont_monad_law> test
+[info] + Monad[Cont[R, ?]].leftIdentity: OK, passed 100 tests.
+[info] + Monad[Cont[R, ?]].rightIdentity: OK, passed 100 tests.
+[info] + Monad[Cont[R, ?]].associativity: OK, passed 100 tests.
+[info] Passed: Total 3, Failed 0, Errors 0, Passed 3
+[success] Total time: 0 s, completed 2019/09/15 19:34:12
diff --git a/tips_10_monad → tips_10_monad.scala b/tips_10_monad → tips_10_monad.scala
diff --git a/tips_11_monad_in_scala.scala b/tips_11_monad_in_scala.scala
@@ -0,0 +1 @@
+w
diff --git a/tips_10_monad b/tips_10_monad
@@ -1 +1,12 @@
-w
+// M[_] はモナドの型
+def pure[A](a: A): M[A]
+def flatMap[B](f: A => M[B]): M[B]
+
+// 右単位元
+fa.flatMap(a => pure(a)) == fa
+
+// 左単位元
+pure(a).flatMap(f) == f(a)
+
+// 結合律
+fa.flatMap(f).flatMap(g) == fa.flatMap(a => f(a).flatMap(g))
diff --git a/practice_11_error_handling.scala b/practice_11_error_handling.scala
@@ -11,8 +11,8 @@ def successValueOr[R, A](fa: Try[A])(ifFailure: Throwable => R): Cont[R, A] =
 // input から指定された key に対応する値を取り出し、数値型に変換する
 def parseInt(input: Map[String, String], key: String): Cont[String, Int] =
   for {
-    s <- someValueOr(input.get(key))("not found")
-    i <- successValueOr(Try(s.toInt))(_.getMessage)
+    s <- someValueOr(input.get(key))(s"not found: $key")
+    i <- successValueOr(Try(s.toInt))(_.toString)
   } yield i
 
 // ===
@@ -27,10 +27,10 @@ parseInt(input, "age").run(i => s"result: $i")
 // ===
 
 scala> parseInt(input, "address").run(i => s"result: $i")
-res95: String = not found
+res99: String = not found: address
 
 scala> parseInt(input, "name").run(i => s"result: $i")
-res96: String = For input string: "aoiroaoino"
+res100: String = java.lang.NumberFormatException: For input string: "aoiroaoino"
 
 scala> parseInt(input, "age").run(i => s"result: $i")
-res97: String = result: 17
+res101: String = result: 17
diff --git a/practice_11_error_handling.scala b/practice_11_error_handling.scala
@@ -17,14 +17,20 @@ def parseInt(input: Map[String, String], key: String): Cont[String, Int] =
 
 // ===
 
-scala> val source = Map("name" -> "aoiroaoino", "age" -> "29")
-source: scala.collection.immutable.Map[String,String] = Map(name -> aoiroaoino, age -> 29)
+// 例えば下記のような input を仮定する
+val input = Map("name" -> "aoiroaoino", "age" -> "17")
 
-scala> parseInt(source, "address").run(i => s"result: $i")
-res92: String = not found
+parseInt(input, "address").run(i => s"result: $i")
+parseInt(input, "name").run(i => s"result: $i")
+parseInt(input, "age").run(i => s"result: $i")
 
-scala> parseInt(source, "name").run(i => s"result: $i")
-res93: String = For input string: "aoiroaoino"
+// ===
+
+scala> parseInt(input, "address").run(i => s"result: $i")
+res95: String = not found
+
+scala> parseInt(input, "name").run(i => s"result: $i")
+res96: String = For input string: "aoiroaoino"
 
-scala> parseInt(source, "age").run(i => s"result: $i")
-res94: String = result: 29
+scala> parseInt(input, "age").run(i => s"result: $i")
+res97: String = result: 17
diff --git a/practice_11_error_handling.scala b/practice_11_error_handling.scala
@@ -16,8 +16,15 @@ def parseInt(input: Map[String, String], key: String): Cont[String, Int] =
   } yield i
 
 // ===
-val source = Map("name" -> "aoiroaoino", "age" -> "29")
 
-parseInt(source, "address").run(i => s"result: $i")
-parseInt(source, "name").run(i => s"result: $i")
-parseInt(source, "age").run(i => s"result: $i")
+scala> val source = Map("name" -> "aoiroaoino", "age" -> "29")
+source: scala.collection.immutable.Map[String,String] = Map(name -> aoiroaoino, age -> 29)
+
+scala> parseInt(source, "address").run(i => s"result: $i")
+res92: String = not found
+
+scala> parseInt(source, "name").run(i => s"result: $i")
+res93: String = For input string: "aoiroaoino"
+
+scala> parseInt(source, "age").run(i => s"result: $i")
+res94: String = result: 29
diff --git a/practice_11_error_handling.scala b/practice_11_error_handling.scala
@@ -1,11 +1,14 @@
 import scala.util.Try
 
+// Some だったら継続に値を渡して実行。None だったら継続を破棄して ifNone の結果を返す
 def someValueOr[R, A](fa: Option[A])(ifNone: => R): Cont[R, A] =
   Cont(ar => fa.fold(ifNone)(ar)) // Cont(fa.fold(ifNone))
 
+// Success だったら継続に値を渡して実行。None だったら継続を破棄して ifFailure の結果を返す
 def successValueOr[R, A](fa: Try[A])(ifFailure: Throwable => R): Cont[R, A] =
   Cont(ar => fa.fold(ifFailure, ar)) // Cont(fa.fold(ifFailure, _))
 
+// input から指定された key に対応する値を取り出し、数値型に変換する
 def parseInt(input: Map[String, String], key: String): Cont[String, Int] =
   for {
     s <- someValueOr(input.get(key))("not found")

diff --git a/practice_10_cond.scala b/practice_10_cond.scala
@@ -1,5 +1,16 @@
 // fizzbuzz
 
+def fizzCont(i: Int): Cont[String, Int] = Cont { ar =>
+  if (i % 3 == 0) {
+    "Fizz" // 継続(ar)を実行しないので計算が "Fizz" で終了する
+  } else {
+    ar(i)  // 継続に i を渡し、残りの処理を実行する
+  }
+}
+
+
+// ===
+
 def fizzCont(i: Int): Cont[String, Int] = Cont(ar => if (i % 3 == 0) "Fizz" else ar(i))
 def buzzCont(i: Int): Cont[String, Int] = Cont(ar => if (i % 5 == 0) "Buzz" else ar(i))
 def fizzBuzzCont(i: Int): Cont[String, Int] = Cont(ar => if (i % 15 == 0) "FizzBuzz" else ar(i))

diff --git a/practice_10_cond.scala b/practice_10_cond.scala
@@ -1 +1,21 @@
-w
+// fizzbuzz
+
+def fizzCont(i: Int): Cont[String, Int] = Cont(ar => if (i % 3 == 0) "Fizz" else ar(i))
+def buzzCont(i: Int): Cont[String, Int] = Cont(ar => if (i % 5 == 0) "Buzz" else ar(i))
+def fizzBuzzCont(i: Int): Cont[String, Int] = Cont(ar => if (i % 15 == 0) "FizzBuzz" else ar(i))
+
+def fizzBuzz(i: Int): Cont[String, Int] =
+  for {
+    a <- fizzBuzzCont(i)
+    b <- fizzCont(a)
+    c <- buzzCont(b)
+  } yield c
+
+// ===
+
+scala> LazyList.from(1).map(fizzBuzz(_).run(_.toString)).take(15).toList
+res54: List[String] = List(1, 2, Fizz, 4, Buzz, Fizz, 7, 8, Fizz, Buzz, 11, Fizz, 13, 14, FizzBuzz)
+
+// ===
+
+
diff --git a/practice_11_error_handling.scala b/practice_11_error_handling.scala
@@ -1 +1,20 @@
-w
+import scala.util.Try
+
+def someValueOr[R, A](fa: Option[A])(ifNone: => R): Cont[R, A] =
+  Cont(ar => fa.fold(ifNone)(ar)) // Cont(fa.fold(ifNone))
+
+def successValueOr[R, A](fa: Try[A])(ifFailure: Throwable => R): Cont[R, A] =
+  Cont(ar => fa.fold(ifFailure, ar)) // Cont(fa.fold(ifFailure, _))
+
+def parseInt(input: Map[String, String], key: String): Cont[String, Int] =
+  for {
+    s <- someValueOr(input.get(key))("not found")
+    i <- successValueOr(Try(s.toInt))(_.getMessage)
+  } yield i
+
+// ===
+val source = Map("name" -> "aoiroaoino", "age" -> "29")
+
+parseInt(source, "address").run(i => s"result: $i")
+parseInt(source, "name").run(i => s"result: $i")
+parseInt(source, "age").run(i => s"result: $i")
diff --git a/practice_10_cond.scala b/practice_10_cond.scala
@@ -0,0 +1 @@
+w
diff --git a/practice_11_error_handling.scala b/practice_11_error_handling.scala
@@ -0,0 +1 @@
+w
diff --git a/practice_12_resource.scala b/practice_12_resource.scala
@@ -0,0 +1 @@
+w
diff --git a/tips_10_monad b/tips_10_monad
@@ -0,0 +1 @@
+w
diff --git a/tips_11_monad_in_scala b/tips_11_monad_in_scala
@@ -0,0 +1 @@
+w
diff --git a/intro_23_cont_monad_for_syntax.scala b/intro_23_cont_monad_for_syntax.scala
@@ -15,7 +15,14 @@ def prog[R]: Cont[R, String] =
 
 // ===
 
+scala> prog.run(s => s.toList)
+res18: List[Char] = List(N, U, M, :,  , 9)
 
+scala> prog.run(s => s.length)
+res19: Int = 6
+
+scala> prog.run(s => s)
+res20: String = NUM: 9
 
 // ===
 

diff --git a/intro_11_calc.scala b/intro_11_calc.scala
@@ -1,5 +1,6 @@
 // ===
 def add(i: Int, j: Int): Int = i + j
+def mul(i: Int, j: Int): Int = i * j
 def show(i: Int): String = "num: " + i.toString
 
 val a = add(1, 2)
@@ -9,33 +10,36 @@ println(s)
 
 // ===
 def add(i: Int, j: Int): Int = i + j
+def mul(i: Int, j: Int): Int = i * j
 def show(i: Int): String = "num: " + i.toString
 
 val a = add(1, 2) // 計算結果
 
 // ↓ その後の計算
-val b = add(a, 3)
+val b = mul(a, 3)
 val s = show(b)
 println(s)
 
 
 // ===
 def add(i: Int, j: Int): Int = i + j
+def mul(i: Int, j: Int): Int = i * j
 def show(i: Int): String = "num: " + i.toString
 
 val a = add(1, 2)
-val b = add(a, 3) // 計算結果
+val b = mul(a, 3) // 計算結果
 
 // その後の計算
 val s = show(b)
 println(s)
 
 // ===
 def add(i: Int, j: Int): Int = i + j
+def mul(i: Int, j: Int): Int = i * j
 def show(i: Int): String = "num: " + i.toString
 
 val a = add(1, 2)
-val b = add(a, 3)
+val b = mul(a, 3)
 val s = show(b) // 計算結果
 
 // その後の計算

diff --git a/intro_13_cps_compose.scala b/intro_13_cps_compose.scala
@@ -2,15 +2,15 @@
 
 // 直接スタイル（再掲）
 val a = add(1, 2)
-val b = add(a, 3)
+val b = mul(a, 3)
 val s = show(b)
 println(s)
 
 // ===
 
 // 継続渡しスタイル
 add(1, 2){ a =>
-  add(a, 3){ b =>
+  mul(a, 3){ b =>
     show(b){ s =>
       println(s)
     }

diff --git a/intro_23_cont_monad_for_syntax.scala b/intro_23_cont_monad_for_syntax.scala
@@ -1,33 +1,27 @@
 // ===
 
 def add[R](i: Int, j: Int): Cont[R, Int] = Cont(ar => ar(i + j))
+def mul[R](i: Int, j: Int): Cont[R, Int] = Cont(ar => ar(i * j))
 def show[R](i: Int): Cont[R, String]     = Cont(ar => ar(s"num: $i"))
 
 def prog[R]: Cont[R, String] =
   for {
     a <- add(1, 2)
-    b <- add(a, 3)
+    b <- mul(a, 3)
     s <- show(b)
   } yield {
     s.toUpperCase
   }
 
 // ===
 
-scala> prog.run(s => s.toList)
-res15: List[Char] = List(N, U, M, :,  , 6)
 
-scala> prog.run(s => s.length)
-res16: Int = 6
-
-scala> prog.run(s => s)
-res17: String = NUM: 6
 
 // ===
 
 def prog[R]: Cont[R, String] =
   add(1, 2).flatMap { a =>
-    add(a, 3).flatMap { b =>
+    mul(a, 3).flatMap { b =>
       show(b).map { s =>
         s.toUpperCase
       }
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