How to deal with List of currying function in Scala - scala

Question

In the following Scala code I have a sequence of currying functions with different signatures. I want to iterate through them and invoke.
def intCheck(b: Int)(a: Int) = a == b
def stringCheck(b: String)(a: String) = a == b
def doubleCheck(b: Double)(a: Double) = a == b
val list = Seq(intCheck(1) _, stringCheck("a") _, doubleCheck(2.3) _)
for (f <- list) {
//if f is 1st function
f(2) // LINE 1
//if f is 2nd function
f("a") // LINE 2
//if f is 3rd function
f(2.0) // LINE 3
}
But for the LINE 1,2 & 3 I get a compilation error "Type mismatch, expected: String with Int with Double, actual: Int". How can I enforce compiler to avoid type-check here if I am sure about the type here.

Answer 1

i think this is a way...
sealed abstract class AnyChecker(val a:Any,val b:Any) {
def eval = a==b
}
class IntChecker(override val a:Int,override val b:Int) extends AnyChecker(a,b)
class DoubleChecker(override val a:Double,override val b:Double) extends AnyChecker(a,b)
class StringChecker(override val a:String,override val b:String) extends AnyChecker(a,b)
object IntChecker {
def apply(a:Int,b:Int) = new IntChecker(a,b)
def unapply(intChecker: IntChecker) = Some(intChecker.a,intChecker.b)
}
object DoubleChecker {
def apply(a:Double,b:Double) = new DoubleChecker(a,b)
def unapply(doubleChecker: DoubleChecker) = Some(doubleChecker.a,doubleChecker.b)
}
object StringChecker {
def apply(a:String,b:String) = new StringChecker(a,b)
def unapply(stringChecker: StringChecker) = Some(stringChecker.a,stringChecker.b)
}
val list = List(IntChecker(1,3), StringChecker("a","a"), DoubleChecker(2.3,3.1), StringChecker("a","b"), StringChecker("a","c"), StringChecker("x","x"))
for (f <- list) {
f match {
case a:IntChecker => println(s"a:${a.a}, b:${a.b}, ${a.eval}")
case a:DoubleChecker => println(s"a:${a.a}, b:${a.b}, ${a.eval}")
case StringChecker("a","a") => println("equals")
case StringChecker("a","b") => println("not equals")
case StringChecker("a",b) => println( StringChecker("a",b).eval)
case StringChecker(a,b) => println(StringChecker(a,b).eval)
}
}
Please, check this, i am sure this will help you.
http://bplawler.tumblr.com/post/7493366722/scala-programming-unapply-and-case-classes
Also, another simple way is only using AnyChcker....
class AnyChecker[T](val a: T, val b: T) {
def eval = a == b
override def toString = s"Checker($a,$b)"
}
object AnyChecker {
def apply[T](a: T, b: T) = new AnyChecker(a, b)
def unapply[T](doubleChecker: AnyChecker[T]) = Some(doubleChecker.a, doubleChecker.b)
}
val list2 = List(AnyChecker(1, 3), AnyChecker("a", "a"), AnyChecker(2.3, 3.1), AnyChecker("a", "b"), AnyChecker("a", "c"), AnyChecker("x", "x"))
for (checker <- list2) {
checker match {
case AnyChecker(1, 3) => println("ints")
case AnyChecker(2.3, 3.1) => println("doubles")
case AnyChecker("a","a") => println("double a")
case checker1: AnyChecker[Any] =>println(checker1)
}
}
if you only write like a tupes....
val list3 = List((1, "1"), ("a", "a"), (2.3, 3.1), ("a", "b"), ("a", "c"), ("x", "x")).map(element=>AnyChecker(element._1,element._2))
for (checker <- list3) {
checker match {
case AnyChecker(1, 3) => println("ints")
case AnyChecker(2.3, 3.1) => println("doubles")
case AnyChecker("a","a") => println("double a")
case checker1: AnyChecker[Any] =>println(checker1.eval)
}
}