Test.gf

abstract Test = {

cat S ;
fun testS : S ;
}

TestCnc.gf

concrete TestCnc of Test = open Prelude in {

lincat S = SS ;
lin testS = mkSS "test" ;

oper
  mkSS : Str -> SS ;

{- - compiling TestCnc.gf... gf: 11-13: In mkSS: unsupported token gluing: str + "bar"
-}
  mkSS str = case str of {
    x + "foo" => ss (x + "bar")
  } ;

 {-  -- This version succeeds:
  mkSS str = case str of {
     x + "foo" => ss (x + "bar")
   ; x => ss (x + "baz")
   } ;
  -}

-- The two versions below give the expected error:
--   gf: Internal error in GeneratePMCFG: evalTerm ("test")

{- -- 1)
  mkSS str = case str of {
     x + "foo" => ss (str + "bar")
  } ;
-}

{- -- 2)
  mkSS str = case str of {
     x + "foo" => ss x
  } ;
-}

}