src/Pure/General/path.ML

     (case getenv s of
       "" => error ("Undefined Isabelle environment variable: " ^ quote s)
     | path => rep (unpack path))
   | eval x = [x];
 
-val expand = rep #> map eval #> List.concat #> norm #> Path;
+val expand = rep #> maps eval #> norm #> Path;
 val position = expand #> pack #> quote #> Position.line_name 1;
 
 end;