polished the syntax grammar for the book

examples/tutorial/syntax/GrammarEng.gf

@@ -6,12 +6,15 @@ concrete GrammarEng of Grammar = open Prelude, MorphoEng in {
     Phr  = {s : Str} ;
     S    = {s : Str} ;
     QS   = {s : Str} ;
+    Cl   = {s : Order => Bool => Str} ;
+    QCl  = {s : Order => Bool => Str} ;
     NP   = NounPhrase ;
     IP   = NounPhrase ;
     CN   = Noun ;
     Det  = {s : Str ; n : Number} ;
     IDet = {s : Str ; n : Number} ;
     AP   = {s : Str} ;
+    Adv  = {s : Str} ;
     AdA  = {s : Str} ;
     VP   = VerbPhrase ;
     N    = Noun ;
@@ -19,36 +22,59 @@ concrete GrammarEng of Grammar = open Prelude, MorphoEng in {
     V    = Verb ;
     V2   = Verb2 ;
     Conj = {s : Str} ;
+    Subj = {s : Str} ;
     Pol  = {s : Str ; p : Bool} ;
 
   lin
-    PhrS = postfixSS "." ;
+    PhrS  = postfixSS "." ;
     PhrQS = postfixSS "?" ;
- 
-    PredVP   = predVP True ;
-    QuestVP  = predVP False ;
-    IPPredVP = predVP True ;
 
-    IPPredV2 p ip np v2 = {
-      s = let 
+    UseCl  pol cl  = {s = pol.s ++ cl.s  ! Dir ! pol.p} ;
+    UseQCl pol qcl = {s = pol.s ++ qcl.s ! Inv ! pol.p} ;
+
+    QuestCl cl = cl ;
+ 
+    SubjS subj s = {s = subj.s ++ s.s} ;
+
+    PredVP = predVP ;
+
+    QuestVP ip vp = let cl = predVP ip vp in  {s = \\_ => cl.s ! Dir};
+
+    QuestV2 ip np v2 = {
+      s = \\ord,pol => 
+          let 
             vp : VerbPhrase = {s = \\q,b,n => predVerb v2 q b n} ;
           in 
-          bothWays (ip.s ++ (predVP False p np vp).s) v2.c
-    } ;
-    
-        
-    ComplV2 v2 np = {
-      s = \\q,b,n => 
-        let vp = predVerb v2 q b n in
-        <vp.p1, vp.p2 ++ v2.c ++ np.s>
+          bothWays (ip.s ++ (predVP np vp).s ! ord ! pol) v2.c
     } ;
 
-    ComplAP ap = {s = \\_,b,n => <copula b n, ap.s>} ;
+    ComplV2 v2 np = {
+      s = \\q,b,n => 
+        let vp = predVerb v2 q b n in {
+          fin = vp.fin ; 
+          inf = vp.inf ++ v2.c ++ np.s
+        }
+    } ;
+
+    ComplAP ap = {
+      s = \\_,b,n => {
+        fin = copula b n ; 
+        inf = ap.s 
+      }
+    } ;
 
     DetCN det cn = {s = det.s ++ cn.s ! det.n ; n = det.n} ;
 
     ModCN ap cn  = {s = \\n => ap.s ++ cn.s ! n} ;
 
+    AdVP adv vp  = {
+      s = \\o,b,n => 
+        let vps = vp.s ! o ! b ! n in {
+          fin = vps.fin ;
+          inf =  vps.inf ++ adv.s
+        }
+    } ;
+
     AdAP ada ap  = {s = ada.s ++ ap.s} ;
 
     IDetCN det cn = {s = det.s ++ cn.s ! det.n ; n = det.n} ;
@@ -70,26 +96,30 @@ concrete GrammarEng of Grammar = open Prelude, MorphoEng in {
     indef_Det = {s = artIndef ; n = Sg} ;
     plur_Det = {s = [] ; n = Pl} ;
     two_Det = {s = "two" ; n = Pl} ;
-
+    today_Adv = {s = "today"} ;
     very_AdA = {s = "very"} ;
-
     which_IDet = {s = "which" ; n = Sg} ;
 
     and_Conj = {s = "and"} ;
+    because_Subj = {s = "because"} ;
 
     PPos = {s = [] ; p = True} ;
     PNeg = {s = [] ; p = False} ;
 
+  param
+    Order = Dir | Inv ;
+
   oper
     NounPhrase = {s : Str ; n : Number} ;
-    VerbPhrase = {s : Bool => Bool => Number => Str * Str} ; -- decl, pol
+    VerbPhrase = {s : Order => Bool => Number => {fin,inf : Str}} ;
 
-    predVP : Bool -> {s : Str ; p : Bool} -> NounPhrase -> VerbPhrase -> SS = 
-      \q,p,np,vp -> {
-      s = let vps = vp.s ! q ! p.p ! np.n 
+    predVP : NounPhrase -> VerbPhrase -> {s : Order => Bool => Str} = 
+      \np,vp -> {
+      s = \\q,p => 
+          let vps = vp.s ! q ! p ! np.n 
           in case q of {
-            True  => p.s ++ np.s ++ vps.p1 ++ vps.p2 ;
-            False => p.s ++ vps.p1 ++ np.s ++ vps.p2
+            Dir => np.s ++ vps.fin ++ vps.inf ;
+            Inv => vps.fin ++ np.s ++ vps.inf
             }
     } ;
 
@@ -101,15 +131,16 @@ concrete GrammarEng of Grammar = open Prelude, MorphoEng in {
     do : Bool -> Number -> Str = \b,n -> 
       posneg b ((mkV "do").s ! n) ;
 
-    predVerb : Verb -> Bool -> Bool -> Number -> Str * Str = \verb,q,b,n -> 
+    predVerb : Verb -> Order -> Bool -> Number -> {fin,inf : Str} = 
+      \verb,q,b,n -> 
       let 
         inf = verb.s ! Pl ;
         fin = verb.s ! n ;
         aux = do b n
       in
       case <q,b> of {
-        <True,True> => <[],fin> ;
-        _ => <aux,inf>
+        <Dir,True> => {fin = []  ; inf = fin} ;
+        _          => {fin = aux ; inf = inf}
         } ;
 
     posneg : Bool -> Str -> Str = \b,do -> case b of {