Fix XML indentation in Emacs mode The return value of MATCH-STRING is a string. At least on Emacs 25, the comparisons between string and character with EQUAL could never succeed, and so the cases for matching braces were never triggered. GET-TEXT-PROPERTY may return a list rather than an atom (for example, on long lines with whitespace-mode turned on), and this broke the heuristic of looking for the tag face in previous text.

fun main wrap =
    let
        fun edit id =
            let
                val r = 0
                fun save () = <xml/>
            in
                wrap (save ())
            end
    in
        edit 0
    end

fun wrap (inside : xbody) = return <xml/>

val main () = main wrap