Fun(ctional programming) with fold-left and transform
Over on StackOverflow someone asked how to apply an XSLT 1.0 stylesheet for merging two XML documents to all XML files in a directory . The approach there in the question as well as the answer is to use a shell script to run the stylesheet with Saxon on two files, then merge the result with a third file and so on. However, given that since XPath 3.1 we have the uri-collection function to process a sequence of files and that XPath 3.1 even offers a transform function to perform a transformation directly in XSLT/XPath I thought it should also be possible to solve the problem completely in XSLT 3.0. Additionally the algorithm to process a sequence of input files, applying the merge transformation repeatedly to each file, accumulating the result, looked like an opportunity to use the fold-left function supported also in XSLT 3.0 since being included in the XPath 3 functions and operators specification. The original XSLT 1.0 stylesheet takes a primary input document and a with par