Xee contains an extensive implementation of XPath 3.1, and a partial implementation of XSLT 3.0. Both use the same compiler/interpreter framework.

Xee does not support XML schemas at present. Only basic atomic types are supported. Optional static typing is not supported, but dynamic type checking does take place.

XPath 1.0 mode is not supported.

Most of the fn library has been implemented. math functions are supported. map and array are both fully supported.

In general, gaps still exist in parsing and formatting, unparsed text, document collections, and JSON support.

See fn.md for details.

XSLT is parsed into a complete AST and a large subset of XSLT works, but there are gaps all over the place.

xsl:template, xsl:value-of, xsl:variable, xsl:if xsl:choose, xsl:when, xsl:otherwise, xsl:for-each, xsl:copy, xsl:copy-of, xsl:sequence, xsl:apply-templates, xsl:text, xsl:attribute, xsl:namespace, xsl:comment, xsl:processing-instruction all have their core behavior implemented.

See xslt.md for details.

One big task is to support XSLT tests in the test runner - the test runner has been prepared for this by making it generic and the test suite has been imported into vendor, but XSLT support in the test runner is not yet implemented.