Null-safe navigation operator (and elvis operator)

Janis Schöck janis at
Tue Jul 9 13:08:12 UTC 2019

Hello compiler-dev List,

I am trying to assert, whether my idea (which is not actually original 
it appears) is valuable for Java.
Apparently kotlin already features the following (null safe navigation 

// returns null if...
// - foo() returns null,
// - or if foo() is non-null, but bar() returns null,
// - or if foo() and bar() are non-null, but baz() returns null.
// vice versa, return value is non-null if and only if foo(), bar() and 
baz() are non-null

In that same context, if an expression would evaluate to null, but a 
primitive type is required, kotlin can
fall back on a default, or evaluate an alternate expression.

val  name:  String  =  maybe  ?:  "stranger"

Independently of kotlin, I think null safe accessing seems to be a 
valuable language feature. Since I did not
know kotlin had this when I started, I put it into a JEP/JSR format to 
collect feedback on. Since I am new to
this list, maybe the primary question: Do I just write up the entire 
JEP-plain text here, or will this just bother
people, as it is a lot of text, and probably will mess up bulked mails?

Secondary question: Is this the correct list to write to, or is this 
better addressed at the amber-project list?

Thank you in advance,
Janis Schöck

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