added the "alter lin" command

src/compiler/GF/Command/Abstract.hs

@@ -17,7 +17,7 @@ data TransactionCommand
    = CreateFun [Option] Fun Type
    | CreateCat [Option] Cat [Hypo]
    | CreateConcrete [Option] ConcName
-   | CreateLin [Option] Fun Term
+   | CreateLin [Option] Fun Term Bool
    | CreateLincat [Option] Cat Term
    | DropFun [Option] Fun
    | DropCat [Option] Cat

src/compiler/GF/Command/Commands.hs

@@ -716,6 +716,20 @@ pgfCommands = Map.fromList [
        ],
      needsTypeCheck = False
      }),
+  ("a", emptyCommandInfo {
+     longname = "alter",
+     syntax = "alter lin f = ..",
+     synopsis = "Dynamically updates the linearization of a function in the current grammar.",
+     explanation = unlines [
+       "The syntax is the same as if the definition was in a module. If you want to use",
+       "any operations inside the lin definition, you should import them",
+       "by using the command `i -resource <file path>`."
+       ],
+     flags = [
+       ("lang","the language in which to alter the lin")
+       ],
+     needsTypeCheck = False
+     }),
   ("d", emptyCommandInfo {
      longname = "drop",
      syntax = "drop fun f; drop cat c; drop concrete l; drop lin c; or drop lincat c",

src/compiler/GF/Command/Parse.hs

@@ -82,7 +82,7 @@ pTransactionCommand = do
           | take 1 cmd == "d" -> do
                name <- pIdent
                return (DropConcrete opts name)
-    "lin" | take 1 cmd == "c" -> do
+    "lin" | elem (take 1 cmd) ["c","a"] -> do
                f <- pIdent
                skipSpaces
                args <- sepBy pIdent skipSpaces
@@ -92,7 +92,7 @@ pTransactionCommand = do
                t  <- readS_to_P (\s -> case runPartial pTerm s of
                                          Right (s,t) -> [(t,s)]
                                          _ -> [])
-               return (CreateLin opts f (foldr (Abs Explicit . identS) t args))
+               return (CreateLin opts f (foldr (Abs Explicit . identS) t args) (take 1 cmd == "a"))
           | take 1 cmd == "d" -> do
                 f <- pIdent
                 return (DropLin opts f)

src/compiler/GF/Interactive.hs

@@ -138,7 +138,7 @@ execute1 readNGF s0 =
                             continue
                           _ -> do putStrLnE $ "no import in history"
                                   continue
-         (w  :ws) | w == "c" || w == "d" -> do
+         (w  :ws) | elem w ["c","a","d"] -> do
                         case readTransactionCommand s0 of
                           Just cmd -> do checkout
                                          env <- gets pgfenv
@@ -282,7 +282,7 @@ transactionCommand (CreateCat opts c ctxt) pgf mb_txnid = do
 transactionCommand (CreateConcrete opts name) pgf mb_txnid = do
   lift $ updatePGF pgf mb_txnid (createConcrete name (return ()))
   return ()
-transactionCommand (CreateLin opts f t) pgf mb_txnid = do
+transactionCommand (CreateLin opts f t is_alter) pgf mb_txnid = do
   sgr <- getGrammar
   lang <- optLang pgf opts
   mo <- maybe (fail "no source grammar in scope") return $
@@ -297,7 +297,7 @@ transactionCommand (CreateLin opts f t) pgf mb_txnid = do
              Just fields -> case runCheck (compileLinTerm sgr mo t (type2term mo ty)) of
                               Ok ((prods,seqtbl,fields'),_)
                                    | fields == fields' -> do
-                                       createLin f prods seqtbl
+                                       (if is_alter then alterLin else createLin) f prods seqtbl
                                        return ()
                                    | otherwise -> fail "The linearization categories in the resource and the compiled grammar does not match"
                               Bad msg      -> fail msg