new pre syntax (as alternative): pre {"o" | "i" => "an" ; _ => "a"}

next-lib/src/english/ResEng.gf

@@ -178,6 +178,10 @@ resource ResEng = ParamX ** open Prelude in {
       "a" ; 
       "an" / strs {"a" ; "e" ; "i" ; "o" ; "A" ; "E" ; "I" ; "O" }
       } ;
+---    artIndef = pre {
+---      "a" | "e" | "i" | "o" | "A" | "E" | "I" | "O" => "an" ;
+---      _ => "a"
+---      } ;
 
     artDef = "the" ;
 

next-lib/src/italian/PhonoIta.gf

@@ -16,5 +16,6 @@ oper
 
   elision : (_,_,_ : Str) -> Str = \il, l', lo -> 
     pre {il ; l' / vocale ; lo / sImpuro} ;
+---    pre {vocale => l' ;  sImpuro => lo ; _ => il} ;
 
 }