/core/src/main/scala/scalaz/Name.scala

http://github.com/scalaz/scalaz · Scala · 131 lines · 118 code · 10 blank · 3 comment · 0 complexity · 2d37ded2bcb6a91f067c274e9b6bdb09 MD5 · raw file

  1. package scalaz
  2. import scala.annotation.tailrec
  3. /** Call by name */
  4. sealed abstract class Name[A] {
  5. def value: A
  6. }
  7. /** Call by need */
  8. final class Need[A] private(private[this] var eval: () => A) extends Name[A] {
  9. lazy val value: A = {
  10. val value0 = eval()
  11. eval = null
  12. value0
  13. }
  14. }
  15. /** Call by value */
  16. final case class Value[A](value: A) extends Name[A]
  17. object Name {
  18. def apply[A](a: => A) = new Name[A] {
  19. def value = a
  20. }
  21. def unapply[A](v: Name[A]): Option[A] = Some(v.value)
  22. implicit val name: Monad[Name] with BindRec[Name] with Comonad[Name] with Distributive[Name] with Traverse1[Name] with Zip[Name] with Unzip[Name] with Align[Name] with Cozip[Name] =
  23. new Monad[Name] with BindRec[Name] with Comonad[Name] with Distributive[Name] with Traverse1[Name] with Zip[Name] with Unzip[Name] with Align[Name] with Cozip[Name] {
  24. override def foldMap1[A, B: Semigroup](fa: Name[A])(f: A => B) = f(fa.value)
  25. override def foldLeft[A, B](fa: Name[A], z: B)(f: (B, A) => B) = f(z, fa.value)
  26. override def foldRight[A, B](fa: Name[A], z: => B)(f: (A, => B) => B) = f(fa.value, z)
  27. def alignWith[A, B, C](f: A \&/ B => C) = (a, b) => Name(f(\&/.Both(a.value, b.value)))
  28. def cozip[A, B](x: Name[A \/ B]) = x.value.bimap(Name(_), Name(_))
  29. def foldMapRight1[A, B](fa: Name[A])(z: A => B)(f: (A, => B) => B) = z(fa.value)
  30. def traverse1Impl[G[_], A, B](fa: Name[A])(f: A => G[B])(implicit G: Apply[G]) = G.map(f(fa.value))(Name(_))
  31. def unzip[A, B](a: Name[(A, B)]) = (Name(a.value._1), Name(a.value._2))
  32. def zip[A, B](a: => Name[A], b: => Name[B]) = Name((a.value, b.value))
  33. def point[A](a: => A) = Name(a)
  34. override def map[A, B](fa: Name[A])(f: A => B) = Name(f(fa.value))
  35. override def ap[A, B](fa: => Name[A])(f: => Name[A => B]) =
  36. Name(f.value apply fa.value)
  37. def bind[A,B](v: Name[A])(f: A => Name[B]): Name[B] = Name(f(v.value).value)
  38. def cobind[A, B](fa: Name[A])(f: Name[A] => B): Name[B] = Name(f(fa))
  39. override def cojoin[A](a: Name[A]): Name[Name[A]] = Name(a)
  40. def copoint[A](p: Name[A]): A = p.value
  41. def distributeImpl[G[_], A, B](fa: G[A])(f: A => Name[B])(implicit G: Functor[G]) =
  42. Name(G.map(fa)(a => f(a).value))
  43. @tailrec
  44. def tailrecM[A, B](a: A)(f: A => Name[A \/ B]): Name[B] =
  45. f(a).value match {
  46. case -\/(a0) => tailrecM(a0)(f)
  47. case \/-(b) => Name(b)
  48. }
  49. }
  50. implicit def nameEqual[A: Equal]: Equal[Name[A]] = new Equal[Name[A]] {
  51. def equal(a1: Name[A], a2: Name[A]): Boolean = Equal[A].equal(a1.value, a2.value)
  52. }
  53. implicit def covariant: IsCovariant[Name] = IsCovariant.force
  54. }
  55. object Need {
  56. def apply[A](a: => A): Need[A] = new Need(() => a)
  57. def unapply[A](x: Need[A]): Option[A] = Some(x.value)
  58. implicit val need: Monad[Need] with BindRec[Need] with Comonad[Need] with Distributive[Need] with Traverse1[Need] with Zip[Need] with Unzip[Need] with Align[Need] with Cozip[Need] =
  59. new Monad[Need] with BindRec[Need] with Comonad[Need] with Distributive[Need] with Traverse1[Need] with Zip[Need] with Unzip[Need] with Align[Need] with Cozip[Need] {
  60. override def foldMap1[A, B: Semigroup](fa: Need[A])(f: A => B) = f(fa.value)
  61. override def foldLeft[A, B](fa: Need[A], z: B)(f: (B, A) => B) = f(z, fa.value)
  62. override def foldRight[A, B](fa: Need[A], z: => B)(f: (A, => B) => B) = f(fa.value, z)
  63. def alignWith[A, B, C](f: A \&/ B => C) = (a, b) => Need(f(\&/.Both(a.value, b.value)))
  64. def cozip[A, B](x: Need[A \/ B]) = x.value.bimap(Need(_), Need(_))
  65. def foldMapRight1[A, B](fa: Need[A])(z: A => B)(f: (A, => B) => B) = z(fa.value)
  66. def traverse1Impl[G[_], A, B](fa: Need[A])(f: A => G[B])(implicit G: Apply[G]) = G.map(f(fa.value))(Need(_))
  67. def unzip[A, B](a: Need[(A, B)]) = (Need(a.value._1), Need(a.value._2))
  68. def zip[A, B](a: => Need[A], b: => Need[B]) = Need((a.value, b.value))
  69. def point[A](a: => A) = Need(a)
  70. override def map[A, B](fa: Need[A])(f: A => B) = Need(f(fa.value))
  71. override def ap[A, B](fa: => Need[A])(f: => Need[A => B]) =
  72. Need(f.value apply fa.value)
  73. def bind[A, B](v: Need[A])(f: A => Need[B]): Need[B] = Need(f(v.value).value)
  74. def cobind[A, B](fa: Need[A])(f: Need[A] => B): Need[B] = Need(f(fa))
  75. override def cojoin[A](a: Need[A]): Need[Need[A]] = Need(a)
  76. def copoint[A](p: Need[A]): A = p.value
  77. def distributeImpl[G[_], A, B](fa: G[A])(f: A => Need[B])(implicit G: Functor[G]) =
  78. Need(G.map(fa)(a => f(a).value))
  79. @tailrec
  80. def tailrecM[A, B](a: A)(f: A => Need[A \/ B]): Need[B] =
  81. f(a).value match {
  82. case -\/(a0) => tailrecM(a0)(f)
  83. case \/-(b) => Need(b)
  84. }
  85. }
  86. implicit def needEqual[A: Equal]: Equal[Need[A]] = new Equal[Need[A]] {
  87. def equal(a1: Need[A], a2: Need[A]): Boolean = Equal[A].equal(a1.value, a2.value)
  88. }
  89. implicit def covariant: IsCovariant[Value] = IsCovariant.force
  90. }
  91. object Value {
  92. implicit val value: Monad[Value] with BindRec[Value] with Comonad[Value] with Distributive[Value] with Traverse1[Value] with Zip[Value] with Unzip[Value] with Align[Value] with Cozip[Value] =
  93. new Monad[Value] with BindRec[Value] with Comonad[Value] with Distributive[Value] with Traverse1[Value] with Zip[Value] with Unzip[Value] with Align[Value] with Cozip[Value] {
  94. override def foldMap1[A, B: Semigroup](fa: Value[A])(f: A => B) = f(fa.value)
  95. override def foldLeft[A, B](fa: Value[A], z: B)(f: (B, A) => B) = f(z, fa.value)
  96. override def foldRight[A, B](fa: Value[A], z: => B)(f: (A, => B) => B) = f(fa.value, z)
  97. def alignWith[A, B, C](f: A \&/ B => C) = (a, b) => Value(f(\&/.Both(a.value, b.value)))
  98. def cozip[A, B](x: Value[A \/ B]) = x.value.bimap(Value(_), Value(_))
  99. def foldMapRight1[A, B](fa: Value[A])(z: A => B)(f: (A, => B) => B) = z(fa.value)
  100. def traverse1Impl[G[_], A, B](fa: Value[A])(f: A => G[B])(implicit G: Apply[G]) = G.map(f(fa.value))(Value(_))
  101. def unzip[A, B](a: Value[(A, B)]) = (Value(a.value._1), Value(a.value._2))
  102. def zip[A, B](a: => Value[A], b: => Value[B]) = Value((a.value, b.value))
  103. def point[A](a: => A) = Value(a)
  104. def bind[A, B](v: Value[A])(f: A => Value[B]): Value[B] = f(v.value)
  105. def cobind[A, B](fa: Value[A])(f: Value[A] => B): Value[B] = Value(f(fa))
  106. override def cojoin[A](a: Value[A]): Value[Value[A]] = Value(a)
  107. def copoint[A](p: Value[A]): A = p.value
  108. def distributeImpl[G[_], A, B](fa: G[A])(f: A => Value[B])(implicit G: Functor[G]) =
  109. Value(G.map(fa)(a => f(a).value))
  110. @tailrec
  111. def tailrecM[A, B](a: A)(f: A => Value[A \/ B]): Value[B] =
  112. f(a).value match {
  113. case -\/(a0) => tailrecM(a0)(f)
  114. case \/-(b) => Value(b)
  115. }
  116. }
  117. implicit def valueEqual[A: Equal]: Equal[Value[A]] = new Equal[Value[A]] {
  118. def equal(a1: Value[A], a2: Value[A]): Boolean = Equal[A].equal(a1.value, a2.value)
  119. }
  120. implicit def covariant: IsCovariant[Value] = IsCovariant.force
  121. }