Declaring function as parameter in method signature

Question

Slowly moving into scala. Can either of these be done (apparently not the way I have them here)?

def genericFunc(param1:String, param2:String, specificFunc(param2:SpecficType):[T]):[T] =
{
    val interim:SpecificType = makeSpecificType(param1,param2)
    specificFunc(interim)
}


def genericFunc(param1:String, param2:String,specificFunc(param2:SpecficType):Object):Object ={
    val interim:SpecificType = makeSpecificType(param1,param2)
    specificFunc(interim)
}

or does the specificFunc need to be a trait/interface.

See also ["What's the difference between => , ()=>, and Unit=>"](http://stackoverflow.com/q/4543228/298389) for different kinds of functions you can pass-in — om-nom-nom, Oct 02 '13 at 19:45

4lex1v · Accepted Answer · 2013-10-02T18:52:15.390

To pass a function as an argument to another function you should have a following method signature:

def genericFunc[T](param1:String, param2:String, specificFunc: SpecficType => T): T = ???

SpecficType => T - is a function type which means that it needs a function which takes one argument of type SpecficType and returns a value of generic type T. Example:

def fromString[A](str: String, f: String => A) = f(str)

fromString("hello", str => str.toCharArray.sum.toInt)

you can optimize this futher:

fromString("hello", _.toCharArray.sum.toInt)

in this case fromString is a higher-order function. HOF are functions which can:

take another function as an argument
return a function

All this stuff is perfectly described in prof. Odersky book on - Programming in Scala

Declaring function as parameter in method signature

1 Answers1