Defining a Map from String to Function in Scala

Question

I am trying to define a Map literal with key: String, value: (Any)=>String. I tried the following, but get a syntax error:

def foo(x         


        

Answer 1

Int => String is not a subclass of Any => String, rather, the contrary. You can't put (replace) an Int => String function when a code expects Any => String, since that code can apply the function with, say, "hi".

@Ben suggestion works, but how is it useful? you can't invoke the function once you get it from the Map.

If you really want to do this, maybe define foo as a partial function:

val foo: PartialFunction[Any, String] = {case i: Int => ....}

Obviously, this will fail at runtime if you pass it a string, but you can always test if the function is ok for use with your parameter by using isDefinedAt. (another alternative may be manifests, but I don't see the value here)