MonadError

[task-reporter.git] / src / main / scala / jp / ymir / taskReporter / core / TSV.scala

diff --git a/src/main/scala/jp/ymir/taskReporter/core/TSV.scala b/src/main/scala/jp/ymir/taskReporter/core/TSV.scala
index 28d9833ad828817d390ac2dacff1eae45edde8ea..541104f8ae3a037bd53501d85c52a4efe664756c 100644 (file)
--- a/src/main/scala/jp/ymir/taskReporter/core/TSV.scala
+++ b/src/main/scala/jp/ymir/taskReporter/core/TSV.scala
@@ -1,12 +1,86 @@
 package jp.ymir.taskReporter.core
 import scala.collection._
 import scala.collection.immutable.StringLike
+import scala.language.higherKinds
+import scalaz._
 
 object TSV {
   type Header = Seq[Symbol]
   type Field  = String
   type Record = Map[Symbol, Field]
 
+  // ---
+  type Failure[   F[_, _], E, R] = E => F[E, R]
+  type Success[A, F[_, _], E, R] = A => F[E, R]
+
+  trait Parser[E, A] {
+    def runParser[F[_, _], R](kf: Failure[F, E, R], ks: Success[A, F, E, R]): F[E, R]
+  }
+
+  implicit def ParserFunctor[E] = new Functor[({type λ[α] = Parser[E, α]})#λ] {
+    def map[A, B](m: Parser[E, A])(f: A => B) = new Parser[E, B] {
+      def runParser[F[_, _], R](kf: Failure[F, E, R], ks: Success[B, F, E, R]): F[E, R] = {
+        def ks_(a: A) = ks(f(a))
+        return m.runParser(kf, ks_)
+      }
+    }
+  }
+
+  implicit def ParserApplicative[E] = new Applicative[({type λ[α] = Parser[E, α]})#λ] {
+    def point[A](a: => A) = new Parser[E, A] {
+      def runParser[F[_, _], R](kf: Failure[F, E, R], ks: Success[A, F, E, R]): F[E, R]
+        = ks(a)
+    }
+    def ap[A, B](m: => Parser[E, A])(fm: => Parser[E, A => B]) = new Parser[E, B] {
+      def runParser[F[_, _], R](kf: Failure[F, E, R], ks: Success[B, F, E, R]): F[E, R] = {
+        def ks_(f: A => B): F[E, R] = {
+          def ks__(a: A) = ks(f(a))
+          return m.runParser(kf, ks__)
+        }
+        return fm.runParser(kf, ks_)
+      }
+    }
+  }
+
+  implicit def ParserMonad[E] = new Monad[({type λ[α] = Parser[E, α]})#λ] {
+    def point[A](a: => A)
+      = implicitly[Applicative[({type λ[α] = Parser[E, α]})#λ]].point(a)
+
+    def bind[A, B](m: Parser[E, A])(f: A => Parser[E, B]) = new Parser[E, B] {
+      def runParser[F[_, _], R](kf: Failure[F, E, R], ks: Success[B, F, E, R]): F[E, R] = {
+        def ks_(a: A) = f(a).runParser(kf, ks)
+        return m.runParser(kf, ks_)
+      }
+    }
+  }
+
+  implicit def ParserMonadError[E] = new MonadError[Parser, E] {
+    def point[A](a: => A)
+      = implicitly[Applicative[({type λ[α] = Parser[E, α]})#λ]].point(a)
+
+    def bind[A, B](m: Parser[E, A])(f: A => Parser[E, B])
+      = implicitly[Monad[({type λ[α] = Parser[E, α]})#λ]].bind(m)(f)
+
+    def handleError[A](m: Parser[E, A])(f: E => Parser[E, A]) = new Parser[E, A] {
+      def runParser[F[_, _], R](kf: Failure[F, E, R], ks: Success[A, F, E, R]): F[E, R] = {
+        def kf_(e: E) = f(e).runParser(kf, ks)
+        return m.runParser(kf_, ks)
+      }
+    }
+
+    def raiseError[A](e: E) = new Parser[E, A] {
+      def runParser[F[_, _], R](kf: Failure[F, E, R], ks: Success[A, F, E, R]): F[E, R]
+        = kf(e)
+    }
+  }
+
+  def runParser[E, A](p: Parser[E, A]): Either[E, A] = {
+    def left (e: E): Either[E, A] = Left(e)
+    def right(x: A): Either[E, A] = Right(x)
+    return p.runParser(left, right)
+  }
+  // ---
+
   def decode[A: FromRecord](tsv: StringLike[_]): Seq[A] = {
     val lines  = tsv.split('\n').filter(!_.isEmpty)
     val header = lines.head.split('\t').map(Symbol(_))