Saxon

On the XPath side, you could wrap the expression in a call on the data() function.

From a Sequence seq, the best way is probably

AtomizingIterator iter = new AtomizingIterator(seq.iterate())

This gives you the typed value rather than the string value, but there's no difference unless your XPath expression is schema-aware.

More generally, you could do

SequenceIterator stringValues = 
    new ItemMappingIterator(seq.iterate(), item->new StringValue(item.getStringValue()));

Thanks! But what then if I want to construct a Sequence from the SequenceIterator? And in what sense is the last solution more general? Do I lose structure via that solution?

To construct a Sequence from a SequenceIterator, use new SequenceExtent(), or new LazySequence(), depending on whether you want the SequenceIterator to be immediately evaluated.

By "more general" I meant that the ItemMappingIterator can be parameterised with any one-to-one mapping function, this particular function is just a special case.