Issue serializing sequences that are members of an array

Evaluating any of the following in FontoXPath

[(1,2)]

[[1,2]?*]

array:append([],  (1,2))

Expected

Evaluates to an array with a sequence; [(1,2)]

Actual

Returns an error “Serialization error: The value of an entry in an array is expected to be a singleton sequence.”

Testlink:

https://xpath.playground.fontoxml.com/?mode=1&variables={}&xml=<root%2F>&xpath=(%3A+-+sequence+items+will+become+individual+members+-+%3A) array{(1%2C+2)}%2C array{[(1%2C+2)]%3F*}%2C (%3A+construct+an+array+with+a+sequence+as+a+member+[(1%2C2)]+%3A) [(1%2C2)]%2C [[(1%2C+2)]%3F*]%2C array%3Aappend([]%2C+(1%2C2)) &context=

It may even be represented correctly in the AST but cannot be serialised.

[DrRataplan]

I improved the error message a bit, It was lying a bit since non-singleton sequences are sometimes valid (in the case of the empty sequence, which is converted to null).

While I like your suggestion for a more raw output format, I am afraid it will get too explicit too fast. I will keep it in the back of my mind though because it might be very valuable in the playground. I hope no one will want to process it in their own production application that depends on FontoXPath.

I’ll close this issue when the error messages PR is integrated. Thanks for bringing this to our attention!

Regards,

Martin

[line-o]

Thanks for taking it into consideration. I understand that it might be out of scope and there is a valid way to get there by explicitly wrapping a sequence in array {}.