Dear Bridger,
> I was wondering if anyone would have an insight for me as to why the
> following expression is wrong:
>
> for $s in ("/a/b/c", "/1/2/3")
> let $t := $s => tokenize("/")[last()]
> return $t
This is due to the grammar rules of XQuery 3.1, which mandate that
“=>” is followed by an “ArrowFunctionSpecifier” and an “ArgumentList”.
Here are some production rules from the spec:
[96] ArrowExpr ::= UnaryExpr ( "=>" ArrowFunctionSpecifier ArgumentList )*
[127] ArrowFunctionSpecifier ::= EQName | VarRef | ParenthesizedExpr
[122] ArgumentList ::= "(" (Argument ("," Argument)*)? ")"
…
The arrow function specifier can be an EQName, a variable reference or
a parenthesized expression. The last one will do the job:
for $s in ("/a/b/c", "/1/2/3")
let $t := ($s => tokenize("/"))[last()]
return $t
Hope this helps,
Christian
[1] https://www.w3.org/TR/xquery-31/#id-arrow-operator
>
> Thanks for your help!
> Best,
> Bridger
>
> PS I don't always remember to look at the optimized query in the Info window,
> but when I do I always get a hint about something; "util:last()" in this case.
>
> correctly
> ```
> for $s in ("/a/b/c", "/1/2/3")
> let $t := tokenize($s, "/")[last()]
> return $t
> ```
> ```
> for $s in ("/a/b/c", "/1/2/3")
> let $t := $s => tokenize("/") => util:last()
> return $t
> ```
