Why are the curly braces required for a minimal Record declaration?

[Brian Goetz]

John and Remi correctly pointed out that some punctuation is necessary, and that having a special rule (like allowing a semicolon instead of a pair of braces) doesn’t really carry its weight, since it only saves one keystroke.  Here’s another reason.

We actually did prototype it originally where you could drop the braces, and say 

     record Foo(int x);

But it doesn’t take long before you start asking “can I omit the braces on an empty class or interface?  what about methods too?”  Which brings us to a general principle that is in play for a feature like this: minimizing the gratuitous differences between records and classes, because we don’t want to burden users with keeping a lot of silly rules in their head like “on tuesdays, you get two braces for the price of one.”  

This principle comes up over and over again; we saw one yesterday on this list (“can I please have non-nullable records”), and there are many more, ranging from the very reasonable-seeming “can I invoke a record constructor by parameter name rather than positionally” to the absurd “can we omit semicolons in records, it’s not incompatible” (yes, we actually got this one.)  

Every one of these differences adds friction:

 - Users have to remember that they can (do the new thing) in records, but not classes;
 - Users will complain “why can’t classes do this too”, and are quite likely to view the glass as being mostly empty rather than partially full;
 - It is harder or less compatible to migrate records to classes, because they will have features that can’t be represented in otherwise-equivalent classes.  

Like all “syntactic sugar”, there is the risk of a sugar high, and the resulting glycemic crash.  We tried to limit the sugar in records to that needed to achieve the semantic goal — nominal tuples.  

> On Apr 25, 2020, at 4:39 PM, Swaranga Sarma <sarma.swaranga at gmail.com> wrote:
> 
> Records is a new feature and does not carry the same baggage as classes do.
> Looking at a minimal Record Point declaration:
> 
> record Point(int x, int y) {}
> 
> Every part of this declaration makes sense to me expect the curly braces
> '{}'. Why is that required if I do no intend do override any part of the
> record?
> 
> I am probably missing something; appreciate the insight.
> 
> -Swaranga