29869 2016-09-26 06:31:13 +0000 Concise syntax for inline functions 2016-12-07 18:35:10 +0000 1 1 1 Unclassified XPath / XQuery / XSLT Requirements for Future Versions Candidate Recommendation PC All NEW P2 normal --- 1 mike jim.melton benito public-qt-comments oldest_to_newest 127529 0 mike 2016-09-26 06:31:13 +0000 Inline functions in XQuery are verbose. Consider fn:sort($employees, function($emp as element(employee)) { $emp/@salary }) Programming in a purely function style becomes a lot easier with a compact syntax for writing inline functions. Compare: XQuery (1) function($x as xs:integer, $y as xs:integer) { $x + $y } XQuery (2) function($x, $y) {$x + $y} Javascript 6 (x, y) => x+y Java 8 (int x, int y) -> x+y Scala (1) (x: Int, y: Int) => x + y Scala (2) _ + _ Haskell \ x y -> x + y Python lambda x, y: x + y A couple of suggestions: (a) Many use cases for simple inline functions take a single item as argument, and we could exploit the existing use of "." for the context item for such cases. For example use \{. + 1} as shorthand for function($x as item()){$x/(. + 1)} allowing constructs such as fn:sort($employees, \{@salary}) (b) For functions without declared types, we could implicitly declare the arguments as $1, $2, etc: \{$1 + $2} allowing fn:sort($employees, \{$1/@salary}) Or we could combine the two ideas with "." being a synonym for ($1 treat as item()), thus fn:sort($employees, \{@salary}) I'm not wedded to the backslash. Alternatives to \{$1+2} would be fn{$1+$2} or {|$1+$2|} or even bare {$1+$2}. 128297 1 benito 2016-12-07 18:35:10 +0000 \{$1 + $2} looks awesome. Although you cannot set a type for $123. But types on anonymous functions are only causing a mess with function coercion anyways {|$1+$2|} is very bad. It is the JSONiq object merge syntax. And the bare {$1+$2} would be confused with JSONiq object creation.