Question

I have just found out this syntax for a scala Map (used here in mutable form)

val m = scala.collection.mutable.Map[String, Int]() m('Hello') = 5 println(m) //PRINTS Map(Hello -> 5) 

Now I’m not sure whether this is syntactic sugar built in to the language, or whether something more fundamental is going on here involving the fact that a map extends a PartialFunction. Could anyone explain?

Answer 1

If you mean (it would be nice if you could be more explicit)

m('Hello') = 5 

that is intended syntactic sugar for

m.update('Hello', 5) 

independent of what m is. This is analogous to

m('Hello') 

which is syntactic sugar for

m.apply('Hello') 

(I’m just reading ‘Programming in Scala’.)