Introduce type RawIdent; only 9 imports of Data.ByteString.Char8 remain

The fact that identifiers are represented as ByteStrings is now an internal
implentation detail in module GF.Infra.Ident. Conversion between ByteString
and identifiers is only needed in the lexer and the Binary instances.

src/compiler/GF/Grammar/MMacros.hs

@@ -26,7 +26,6 @@ import GF.Grammar.Values
 import GF.Grammar.Macros
 
 import Control.Monad
-import qualified Data.ByteString.Char8 as BS
 import Text.PrettyPrint
 
 {-
@@ -238,11 +237,11 @@ qualifTerm m  = qualif [] where
     Cn c  -> Q (m,c)
     Con c -> QC (m,c)
     _ -> composSafeOp (qualif xs) t
-  chV x = string2var $ ident2bs x
+  chV x = string2var $ ident2raw x
     
-string2var :: BS.ByteString -> Ident
-string2var s = case BS.unpack s of
-  c:'_':i -> identV (BS.singleton c) (readIntArg i) ---
+string2var :: RawIdent -> Ident
+string2var s = case showRawIdent s of
+  c:'_':i -> identV (rawIdentS [c]) (readIntArg i) ---
   _       -> identC s
 
 -- | reindex variables so that they tell nesting depth level
@@ -254,7 +253,7 @@ reindexTerm = qualif (0,[]) where
     Vr x       -> Vr $ look x g
     _ -> composSafeOp (qualif dg) t
   look x  = maybe x id . lookup x --- if x is not in scope it is unchanged
-  ind x d = identC $ ident2bs x `BS.append` BS.singleton '_' `BS.append` BS.pack (show d)
+  ind x d = identC $ ident2raw x `prefixRawIdent` rawIdentS "_" `prefixRawIdent` rawIdentS (show d)
 
 {-
 -- this method works for context-free abstract syntax