Started with unions.

src/GF/Infra/Modules.hs

@@ -44,6 +44,7 @@ data ModuleType i =
   | MTInterface
   | MTInstance i 
   | MTReuse (MReuseType i)
+  | MTUnion (ModuleType i) [(i,[i])] --- not meant to be recursive
   deriving (Eq,Show)
 
 data MReuseType i = MRInterface i | MRInstance i i | MRResource i
@@ -245,21 +246,25 @@ lookupInfo mo i = lookupTree show i (jments mo)
 
 isModAbs m = case mtype m of
   MTAbstract -> True
+----  MTUnion t -> isModAbs t
   _ -> False
 
 isModRes m = case mtype m of
   MTResource -> True
   MTReuse _ -> True
+----  MTUnion t -> isModRes t --- maybe not needed, since eliminated early
   MTInterface -> True ---
   MTInstance _ -> True
   _ -> False
 
 isModCnc m = case mtype m of
   MTConcrete _ -> True
+----  MTUnion t -> isModCnc t
   _ -> False
 
 isModTrans m = case mtype m of
   MTTransfer _ _ -> True
+----  MTUnion t -> isModTrans t
   _ -> False
 
 sameMType m n = case (m,n) of

src/GF/Infra/ReadFiles.hs

@@ -181,16 +181,21 @@ importsOfFile =
   getModuleHeader .          -- analyse into mod header
   filter (not . spec) .      -- ignore keywords and special symbols
   unqual .                   -- take away qualifiers
+  unrestr .                  -- take away union restrictions
   takeWhile (not . term) .   -- read until curly or semic
   lexs .                     -- analyse into lexical tokens
   unComm                     -- ignore comments before the headed line
  where
     term = flip elem ["{",";"]
-    spec = flip elem ["of", "open","in",":", "->","=", "(", ")",",","**"]
+    spec = flip elem ["of", "open","in",":", "->","=", "(", ")",",","**","union"]
     unqual ws = case ws of
       "(":q:ws' -> unqual ws'
       w:ws' -> w:unqual ws'
       _ -> ws
+    unrestr ws = case ws of
+      "[":ws' -> unrestr $ tail $ dropWhile (/="]") ws'
+      w:ws' -> w:unrestr ws'
+      _ -> ws
 
 getModuleHeader :: [String] -> ModuleHeader -- with, reuse
 getModuleHeader ws = case ws of