07-operator-precedence.md

The precedence of Hack operators is shown in the table below.

Operators higher in the table have a higher precedence (binding more tightly). Binary operators on the same row are evaluated according to their associativity.

Operator	Description	Associativity
\	Namespace separator	Left
::	Scope resolution	Left
[]	Index resolution for Hack Arrays and Strings	Left
->, ?->	Property selection and null-safe property selection	Left
new	Object creation & Memory allocation	None
#, ()	Enum class labels and Function calling	Left
clone	Object cloning (shallowly, not deeply)	None
readonly, await, ++ -- (postfix)	Using readonly, Suspending an async function, and Incrementing / Decrementing (postfix)	Right
(int) (float) (string), **, @, ++ -- (prefix)	Casting, Exponentiation, Suppressing errors, and Incrementing / Decrementing (prefix)	Right
is, as ?as	Type checks / Type assertions	Left
!, ~, + - (one argument)	Logical negation, Bitwise negation, and Unary Addition / Subtraction	Right
* / %	Multiplication, Division, and Modulo	Left
., + - (two arguments)	String concatenation and Addition / Subtraction	Left
<< >>	Bitwise shifting (left and right)	Left
< <= > >=, <=>	Comparison operators and Spaceship operator	None
=== !== == !=	Equality operators	None
&	Bitwise AND	Left
^	Bitwise XOR	Left
|	Bitwise OR	Left
&&	Logical AND	Left
||	Logical OR	Left
??	Coalesce operator	Right
? :, ?:	Ternary evaluation and Elvis operator	Left
|>	Pipe / Chain function calls	Left
= += -= .= *= /= %= <<= >>= &= ^= |=, ??=	Assignment operators and Coalescing assignment operator	Right
echo	Write to standard output	Right
include require	Include or Require a script	Left