Simple rules to determine the scope of underscore: If the underscore is an argument to a method, then the scope will be outside that method, otherwise respective the rules below; If the underscore is inside an expression delimited by () or {}, the innermost such delimiter that contains the underscore will be used; All other … Read more
It expands to: myStrings.foreach(println(x => x.toString)) You want: myStrings.foreach(x => println(x.toString)) The placeholder syntax for anonymous functions replaces the smallest possible containing expression with a function.
When you wrote: WithUnit(value = _, unit = “cm”) You wanted it to mean: x => WithUnit(value = x, unit = “cm”) But if you take a close look at the error message, you’ll see that the compiler didn’t see it that way, it parsed it as: WithUnit(x => value = x, unit = “cm”}) … Read more