Parentheses and operator precedence

In general an expression may be enclosed in parentheses without changing its meaning.

If parentheses are not used, operator precedence follows the sequence below, starting with the operators that bind most tightly. Within each group the operators are evaluated left-to-right.

Operator	Meaning
unary `?`	unary lookup operator
`[]`, `()`, binary `?`	predicate, function call, lookup operator
`/`, `//`	path operator
`!`	simple mapping operator
unary `-`, unary `+`	unary plus and minus
`=>`	arrow operator
`cast as`	dynamic type conversion
`castable as`	type test
`treat as`	static type conversion
`instance of`	type test
`except`, `intersect`	set difference and intersection
`\|`, `union`	union operation on sets
`*`, `div`, `idiv`, `mod`	multiply, divide, integer divide, modulo
`+`, `-`	plus, minus
`to`	range expression
`\|\|`	string concatenation (XPath 3.0)
`=`, `!=`, `is`, `<`, `<=;`, `>`, `>=`, `eq`, `ne`, `lt`, `le`, `gt`, `ge`	comparisons
`and`	Boolean and
`or`	Boolean or
`if`	conditional expressions
`some`, `every`	quantified expressions
`let`	variable declaration (XPath 3.0)
`for`	iteration (mapping) over a sequence
`,` (comma)	Sequence concatenation

The various operators are described, in roughly the above order, in the sections that follow.