for and let clauses in the same expression

When a FLWOR expression contains both for and let clauses, the variable bindings that are generated by let clauses are added to the variable bindings that are generated by the for clauses.

In the following example, the for clause includes a variable called $a and an expression that constructs the sequence (1, 2, 3). The let clause includes a variable called $b and an expression that constructs the sequence (4, 5, 6):

for $a in (1, 2, 3)
let $b := (4, 5, 6)
return <output>{$a, $b}</output>

The for and let clauses in this example result in three tuples of bindings. The number of tuples is determined by the for clause.

($a = 1, $b = 4 5 6)
($a = 2, $b = 4 5 6)
($a = 3, $b = 4 5 6)

The return clause in the example executes once for each tuple of bindings. The expression results in the following output:

<output>1 4 5 6</output>
<output>2 4 5 6</output>
<output>3 4 5 6</output>