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author | Gilles Dubochet <gilles.dubochet@epfl.ch> | 2005-12-16 18:44:33 +0000 |
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committer | Gilles Dubochet <gilles.dubochet@epfl.ch> | 2005-12-16 18:44:33 +0000 |
commit | 53a3cc7b17f4cf97075b7e71720777fd84109696 (patch) | |
tree | 0cc784e0b47ea49cc151a136d19f20bfa8ee2197 /sources/examples/monads | |
parent | df50e05006b43b007c2587549030d24b5c154398 (diff) | |
download | scala-53a3cc7b17f4cf97075b7e71720777fd84109696.tar.gz scala-53a3cc7b17f4cf97075b7e71720777fd84109696.tar.bz2 scala-53a3cc7b17f4cf97075b7e71720777fd84109696.zip |
Created proper 'docs' folder for new layout.
Diffstat (limited to 'sources/examples/monads')
-rw-r--r-- | sources/examples/monads/callccInterpreter.scala | 84 | ||||
-rw-r--r-- | sources/examples/monads/directInterpreter.scala | 55 | ||||
-rw-r--r-- | sources/examples/monads/errorInterpreter.scala | 86 | ||||
-rw-r--r-- | sources/examples/monads/simpleInterpreter.scala | 75 | ||||
-rw-r--r-- | sources/examples/monads/stateInterpreter.scala | 86 |
5 files changed, 0 insertions, 386 deletions
diff --git a/sources/examples/monads/callccInterpreter.scala b/sources/examples/monads/callccInterpreter.scala deleted file mode 100644 index 934fce1a9e..0000000000 --- a/sources/examples/monads/callccInterpreter.scala +++ /dev/null @@ -1,84 +0,0 @@ -object callccInterpreter { - - type Answer = Value; - - case class M[A](in: (A => Answer) => Answer) { - def bind[B](k: A => M[B]) = M[B](c => in (a => k(a) in c)); - def map[B](f: A => B): M[B] = bind(x => unitM(f(x))); - def flatMap[B](f: A => M[B]): M[B] = bind(f); - } - - def unitM[A](a: A) = M[A](c => c(a)); - - def showM(m: M[Value]): String = (m in id).toString(); - - def callCC[A](h: (A => M[A]) => M[A]) = - M[A](c => h(a => M[A](d => c(a))) in c); - - type Name = String; - - trait Term; - case class Var(x: Name) extends Term; - case class Con(n: int) extends Term; - case class Add(l: Term, r: Term) extends Term; - case class Lam(x: Name, body: Term) extends Term; - case class App(fun: Term, arg: Term) extends Term; - case class Ccc(x: Name, t: Term) extends Term; - - trait Value; - case object Wrong extends Value { - override def toString() = "wrong" - } - case class Num(n: int) extends Value { - override def toString() = n.toString(); - } - case class Fun(f: Value => M[Value]) extends Value { - override def toString() = "<function>" - } - - type Environment = List[Pair[Name, Value]]; - - def lookup(x: Name, e: Environment): M[Value] = e match { - case List() => unitM(Wrong) - case Pair(y, b) :: e1 => if (x == y) unitM(b) else lookup(x, e1) - } - - def add(a: Value, b: Value): M[Value] = Pair(a, b) match { - case Pair(Num(m), Num(n)) => unitM(Num(m + n)) - case _ => unitM(Wrong) - } - - def apply(a: Value, b: Value): M[Value] = a match { - case Fun(k) => k(b) - case _ => unitM(Wrong) - } - - def interp(t: Term, e: Environment): M[Value] = t match { - case Var(x) => lookup(x, e) - case Con(n) => unitM(Num(n)) - case Add(l, r) => for (val a <- interp(l, e); - val b <- interp(r, e); - val c <- add(a, b)) - yield c - case Lam(x, t) => unitM(Fun(a => interp(t, Pair(x, a) :: e))) - case App(f, t) => for (val a <- interp(f, e); - val b <- interp(t, e); - val c <- apply(a, b)) - yield c - case Ccc(x, t) => callCC(k => interp(t, Pair(x, Fun(k)) :: e)) - } - - def test(t: Term): String = - showM(interp(t, List())); - - val term0 = App(Lam("x", Add(Var("x"), Var("x"))), Add(Con(10), Con(11))); - val term1 = App(Con(1), Con(2)); - val term2 = Add(Con(1), Ccc("k", Add(Con(2), App(Var("k"), Con(4))))); - - def main(args: Array[String]) = { - System.out.println(test(term0)); - System.out.println(test(term1)); - System.out.println(test(term2)); - } -} - diff --git a/sources/examples/monads/directInterpreter.scala b/sources/examples/monads/directInterpreter.scala deleted file mode 100644 index 0e2aae4a7b..0000000000 --- a/sources/examples/monads/directInterpreter.scala +++ /dev/null @@ -1,55 +0,0 @@ -object directInterpreter { - - type Name = String; - - trait Term; - case class Var(x: Name) extends Term; - case class Con(n: int) extends Term; - case class Add(l: Term, r: Term) extends Term; - case class Lam(x: Name, body: Term) extends Term; - case class App(fun: Term, arg: Term) extends Term; - - trait Value; - case object Wrong extends Value; - case class Num(n: int) extends Value; - case class Fun(f: Value => Value)extends Value; - - def showval(v: Value): String = v match { - case Wrong => "<wrong>" - case Num(n) => n.toString() - case Fun(f) => "<function>" - } - - type Environment = List[Pair[Name, Value]]; - - def lookup(x: Name, e: Environment): Value = e match { - case List() => Wrong - case Pair(y, b) :: e1 => if (x == y) b else lookup(x, e1) - } - - def add(a: Value, b: Value): Value = Pair(a, b) match { - case Pair(Num(m), Num(n)) => Num(m + n) - case _ => Wrong - } - - def apply(a: Value, b: Value) = a match { - case Fun(k) => k(b) - case _ => Wrong - } - - def interp(t: Term, e: Environment): Value = t match { - case Var(x) => lookup(x, e) - case Con(n) => Num(n) - case Add(l, r) => add(interp(l, e), interp(r, e)) - case Lam(x, t) => Fun(a => interp(t, Pair(x, a) :: e)) - case App(f, t) => apply(interp(f, e), interp(t, e)) - } - - def test(t: Term): String = - showval(interp(t, List())); - - val term0 = App(Lam("x", Add(Var("x"), Var("x"))), Add(Con(10), Con(11))); - - def main(args: Array[String]) = - System.out.println(test(term0)); -} diff --git a/sources/examples/monads/errorInterpreter.scala b/sources/examples/monads/errorInterpreter.scala deleted file mode 100644 index 05dc979621..0000000000 --- a/sources/examples/monads/errorInterpreter.scala +++ /dev/null @@ -1,86 +0,0 @@ -object errorInterpreter { - - trait M[A] { - def show: String; - def bind[B](k: A => M[B]); - def map[B](f: A => B): M[B] = bind(x => unitM(f(x))); - def flatMap[B](f: A => M[B]): M[B] = bind(f); - } - - def unitM[A](a: A): M[A] = new Suc(a); - def errorM[A](msg: String): M[A] = new Err(msg); - - def showM(m: M[Value]): String = m.show; - - class Suc[A](x: T) extends M[A] { - def bind[A](k: A => M[B]): M[B] = k(x); - def show: String = "Success: " + x; - } - class Err[T](msg: String) extends M[T] { - def bind[A](k: A => M[B]): M[B] = new Err(msg); - def show: String = "Error: " + msg; - } - - type Name = String; - - trait Term; - case class Var(x: Name) extends Term; - case class Con(n: int) extends Term; - case class Add(l: Term, r: Term) extends Term; - case class Lam(x: Name, body: Term) extends Term; - case class App(fun: Term, arg: Term) extends Term; - - trait Value; - case object Wrong extends Value { - override def toString() = "wrong" - } - case class Num(n: int) extends Value { - override def toString() = n.toString(); - } - case class Fun(f: Value => M[Value]) extends Value { - override def toString() = "<function>" - } - - type Environment = List[Pair[Name, Value]]; - - def lookup(x: Name, e: Environment): M[Value] = e match { - case List() => errorM("unbound variable: " + x); - case Pair(y, b) :: e1 => if (x == y) unitM(b) else lookup(x, e1) - } - - def add(a: Value, b: Value): M[Value] = Pair(a, b) match { - case Pair(Num(m), Num(n)) => unitM(Num(m + n)) - case _ => errorM("should be numbers: " + a + "," + b) - } - - def apply(a: Value, b: Value): M[Value] = a match { - case Fun(k) => k(b) - case _ => errorM("should be function: " + a); - } - - def interp(t: Term, e: Environment): M[Value] = t match { - case Var(x) => lookup(x, e) - case Con(n) => unitM(Num(n)) - case Add(l, r) => for (val a <- interp(l, e); - val b <- interp(r, e); - val c <- add(a, b)) - yield c - case Lam(x, t) => unitM(Fun(a => interp(t, Pair(x, a) :: e))) - case App(f, t) => for (val a <- interp(f, e); - val b <- interp(t, e); - val c <- apply(a, b)) - yield c - } - - def test(t: Term): String = - showM(interp(t, List())); - - val term0 = App(Lam("x", Add(Var("x"), Var("x"))), Add(Con(10), Con(11))); - val term1 = App(Con(1), Con(2)); - - def main(args: Array[String]) = { - System.out.println(test(term0)); - System.out.println(test(term1)); - } -} - diff --git a/sources/examples/monads/simpleInterpreter.scala b/sources/examples/monads/simpleInterpreter.scala deleted file mode 100644 index d728c620cf..0000000000 --- a/sources/examples/monads/simpleInterpreter.scala +++ /dev/null @@ -1,75 +0,0 @@ -object simpleInterpreter { - - case class M[A](value: A) { - def bind[B](k: A => M[B]): M[B] = k(value); - def map[B](f: A => B): M[B] = bind(x => unitM(f(x))); - def flatMap[B](f: A => M[B]): M[B] = bind(f); - } - - def unitM[A](a: A): M[A] = M(a); - - def showM(m: M[Value]): String = m.value.toString(); - - type Name = String; - - trait Term; - case class Var(x: Name) extends Term; - case class Con(n: int) extends Term; - case class Add(l: Term, r: Term) extends Term; - case class Lam(x: Name, body: Term) extends Term; - case class App(fun: Term, arg: Term) extends Term; - - trait Value; - case object Wrong extends Value { - override def toString() = "wrong" - } - case class Num(n: int) extends Value { - override def toString() = n.toString(); - } - case class Fun(f: Value => M[Value]) extends Value { - override def toString() = "<function>" - } - - type Environment = List[Pair[Name, Value]]; - - def lookup(x: Name, e: Environment): M[Value] = e match { - case List() => unitM(Wrong) - case Pair(y, b) :: e1 => if (x == y) unitM(b) else lookup(x, e1) - } - - def add(a: Value, b: Value): M[Value] = Pair(a, b) match { - case Pair(Num(m), Num(n)) => unitM(Num(m + n)) - case _ => unitM(Wrong) - } - - def apply(a: Value, b: Value): M[Value] = a match { - case Fun(k) => k(b) - case _ => unitM(Wrong) - } - - def interp(t: Term, e: Environment): M[Value] = t match { - case Var(x) => lookup(x, e) - case Con(n) => unitM(Num(n)) - case Add(l, r) => for (val a <- interp(l, e); - val b <- interp(r, e); - val c <- add(a, b)) - yield c - case Lam(x, t) => unitM(Fun(a => interp(t, Pair(x, a) :: e))) - case App(f, t) => for (val a <- interp(f, e); - val b <- interp(t, e); - val c <- apply(a, b)) - yield c - } - - def test(t: Term): String = - showM(interp(t, List())); - - val term0 = App(Lam("x", Add(Var("x"), Var("x"))), Add(Con(10), Con(11))); - val term1 = App(Con(1), Con(2)); - - def main(args: Array[String]) = { - System.out.println(test(term0)); - System.out.println(test(term1)); - } -} - diff --git a/sources/examples/monads/stateInterpreter.scala b/sources/examples/monads/stateInterpreter.scala deleted file mode 100644 index 593f2d9e3e..0000000000 --- a/sources/examples/monads/stateInterpreter.scala +++ /dev/null @@ -1,86 +0,0 @@ -package examples.monads; - -object stateInterpreter { - - type State = int; - - val tickS = new M(s => Pair((), s + 1)); - - case class M[A](in: State => Pair[A, State]) { - def bind[B](k: A => M[B]) = M[B]{ s0 => - val Pair(a, s1) = this in s0; k(a) in s1 - } - def map[B](f: A => B): M[B] = bind(x => unitM(f(x))); - def flatMap[B](f: A => M[B]): M[B] = bind(f); - } - - def unitM[A](a: A) = M[A](s => Pair(a, s)); - - def showM(m: M[Value]): String = { - val Pair(a, s1) = m in 0; - "Value: " + a + "; Count: " + s1 - } - - type Name = String; - - trait Term; - case class Var(x: Name) extends Term; - case class Con(n: int) extends Term; - case class Add(l: Term, r: Term) extends Term; - case class Lam(x: Name, body: Term) extends Term; - case class App(fun: Term, arg: Term) extends Term; - - trait Value; - case object Wrong extends Value { - override def toString() = "wrong" - } - case class Num(n: int) extends Value { - override def toString() = n.toString(); - } - case class Fun(f: Value => M[Value]) extends Value { - override def toString() = "<function>" - } - - type Environment = List[Pair[Name, Value]]; - - def lookup(x: Name, e: Environment): M[Value] = e match { - case List() => unitM(Wrong) - case Pair(y, b) :: e1 => if (x == y) unitM(b) else lookup(x, e1) - } - - def add(a: Value, b: Value): M[Value] = Pair(a, b) match { - case Pair(Num(m), Num(n)) => for (val _ <- tickS) yield Num(m + n) - case _ => unitM(Wrong) - } - - def apply(a: Value, b: Value): M[Value] = a match { - case Fun(k) => for (val _ <- tickS; val c <- k(b)) yield c - case _ => unitM(Wrong) - } - - def interp(t: Term, e: Environment): M[Value] = t match { - case Var(x) => lookup(x, e) - case Con(n) => unitM(Num(n)) - case Add(l, r) => for (val a <- interp(l, e); - val b <- interp(r, e); - val c <- add(a, b)) - yield c - case Lam(x, t) => unitM(Fun(a => interp(t, Pair(x, a) :: e))) - case App(f, t) => for (val a <- interp(f, e); - val b <- interp(t, e); - val c <- apply(a, b)) - yield c - } - - def test(t: Term): String = - showM(interp(t, List())); - - val term0 = App(Lam("x", Add(Var("x"), Var("x"))), Add(Con(10), Con(11))); - val term1 = App(Con(1), Con(2)); - - def main(args: Array[String]) = { - System.out.println(test(term0)); - System.out.println(test(term1)); - } -} - |