::= Gap

infix ::=

The rules for ::= have not been written yet. Everything below is extracted rather than authored: the official documentation supplies the classification, and the interpreters were asked directly about the rest.

What is established #

Classification #

::= is parsed as an infix at the list prefix precedence level, right-associative.

That is level 23 of 27 on the ladder, counting from the tightest. Operators sharing a level bind equally; grouping among them is decided by associativity alone.

Shares its precedence level with #

:=, ..., !!!, ???.

These all bind equally tightly, so an expression mixing them groups by associativity alone.

What the interpreter said #

Raku++ does not parse this spelling. Asked to compile:

my $a = 6; my $b = 3; sink($a ::= $b)

…it produced a parse error. Any rule written here would describe Raku the language rather than this implementation.

Covered upstream #

The official documentation has a section for this construct: docs.raku.org. Until the rules here are written, that is the better reference.