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yanns/ana.scala

Last active June 11, 2018 14:55
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ana.scala
type Algebra[F[_], A] = F[A] => A
def cata[F[_], R, A](algebra: Algebra[F, A], out: R ⇒ F[R])(r: R)(implicit F: Functor[F]): A =
algebra(F.map(cata(algebra, out))(out(r)))
type Coalgebra[F[_], A] = A => F[A]
def ana[F[_], R, A](coalgebra: Coalgebra[F, A], in: F[R] ⇒ R)(a: A)(implicit F: Functor[F]): R =
in(F.map(ana(coalgebra, in))(coalgebra(a)))
def hylo[F[_], A, B](coalgebra: Coalgebra[F, A], algebra: Algebra[F, B])
(a: A)(implicit F: Functor[F]): B =
algebra(F.map(hylo(coalgebra, algebra))(coalgebra(a)))
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