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// -----------------------------------------------------------------------------
//
// Scalax - The Scala Community Library
// Copyright (c) 2005-8 The Scalax Project. All rights reserved.
//
// The primary distribution site is http://scalax.scalaforge.org/
//
// This software is released under the terms of the Revised BSD License.
// There is NO WARRANTY. See the file LICENSE for the full text.
//
// -----------------------------------------------------------------------------
package scala.tools.scalap
package scalax
package rules
trait Monad[+A] extends Functor[A] {
type M[+A] <: Monad[A]
def flatMap[B](f : A => M[B]) : M[B]
}
trait Monads extends UnitFunctors {
type M[+A] <: Monad[A]
trait Monad[+A] extends Functor[A] with rules.Monad[A] { this : M[A] =>
def map[B](f : A => B) = flatMap { a => unit(f(a)) }
}
trait ZeroMonad extends Monad[Nothing] with ZeroFunctor { this : M[Nothing] =>
def flatMap[B](f : Nothing => M[B]) : M[B] = this
}
}
trait StateReader extends Monads {
type S
def get : M[S]
def read[A](f : S => A) : M[A]
def set(s : => S) : M[S]
def update(f : S => S) : M[S]
}
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