1 package Main

     2 

     3 abstract class Term

     4 case class Var(name: String) extends Term

     5 case class Fun(arg: String, body: Term) extends Term

     6 case class Appli(f: Term, v: Term) extends Term

     7 

     8 object TermTest extends App {

     9   def printTerm(term: Term) {

    10     term match {

    11       case Var(n) =>

    12         print("" + n)

    13       case Fun(x, b) =>

    14         print("^" + x + ".")

    15         printTerm(b)

    16       case Appli(f, v) =>

    17         Console.print("(")

    18         printTerm(f)

    19         print(" ")

    20         printTerm(v)

    21         print(")")

    22     }

    23   }

    24   def isIdentityFun(term: Term): Boolean = term match {

    25     case Fun(x, Var(y)) if x == y => true

    26     case _ => false

    27   }

    28   val id = Fun("x", Var("x"))

    29   println("id: " + id)

    30   val t = Fun("x", Fun("y", Appli(Var("x"), Var("y"))))

    31   println("t: " + t)

    32   printTerm(t)

    33   println

    34   println(isIdentityFun(id))

    35   println(isIdentityFun(t))

    36 }