Optional Chaining Operator

Symbol: ?.
Translated to JavaScript optional chaining operator.

Optional field getting

You can get b field from a map in two ways:

?. a 'b'

or:

a?.b

Optional field getting by dynamic key

= a : (key 2)

= b 'key'

?. a b

Function calls

?.b a

equals to:

?. a b

You can call function b if it exists in map a with parameter 1 with such syntax:

?.b a 1