Use capitalized letters for variables in paren version

collects/datalog/scribblings/datalog.scrbl

@@ -136,9 +136,7 @@ The Datalog REPL accepts new statements that are executed as if they were in the
 
 The semantics of this language is the same as the normal Datalog language, except it uses a @secref["parenstx"].
 
-Literals are represented as S-expressions with identifiers for constant symbols, strings for constant strings, and @racket[,id] for variable symbols.
-
-@racket[unquote], top-level identifiers, and strings are not otherwise allowed in the program.
+Literals are represented as S-expressions with non-capitalized identifiers for constant symbols, strings for constant strings, and capitalized identifiers for variable symbols. Top-level identifiers and strings are not otherwise allowed in the program.
 
 The following is a program:
 @racketmod[datalog/sexp
@@ -147,12 +145,12 @@ The following is a program:
 (! (edge b c))
 (! (edge c d))
 (! (edge d a))
-(! (:- (path ,X ,Y)
-       (edge ,X ,Y)))
-(! (:- (path ,X ,Y)
-       (edge ,X ,Z)
-       (path ,Z ,Y)))
-(? (path ,X ,Y))]
+(! (:- (path X Y)
+       (edge X Y)))
+(! (:- (path X Y)
+       (edge X Z)
+       (path Z Y)))
+(? (path X Y))]
 
 The Parenthetical Datalog REPL accepts new statements that are executed as if they were in the original program text.
 
@@ -168,8 +166,6 @@ The Parenthetical Datalog REPL accepts new statements that are executed as if th
 
 @defform[(= term term)]{ An equality literal. }
 
-@defform[(unquote symbol)]{ A variable symbol. }
-
 @include-section["racket.scrbl"]
 
 @section{Acknowledgments}

collects/datalog/sexp/lang.rkt

@@ -9,8 +9,6 @@
 
 (define-syntax-parameter top
   (λ (stx) (raise-syntax-error '#%top "undefined identifier" stx)))
-(define-syntax-parameter unquote
-  (λ (stx) (raise-syntax-error 'unquote "only allowed inside literals" stx)))
 (define-syntax-parameter datum
   (λ (stx) (raise-syntax-error '#%datum "only allowed inside literals" stx)))
 
@@ -18,15 +16,11 @@
   (syntax-parse 
    stx
    [(_ . sym:id)
+    (if (char-upper-case? (string-ref (symbol->string (syntax->datum #'sym)) 0))
         (quasisyntax/loc stx
-      (constant #'#,stx 'sym))]))
-
-(define-syntax (literal-unquote stx)
-  (syntax-parse 
-   stx
-   [(_ sym:id)
+      (variable #'#,stx 'sym))
         (quasisyntax/loc stx
-      (variable #'#,stx 'sym))]))
+          (constant #'#,stx 'sym)))]))
 
 (define-syntax (literal-datum stx)
   (syntax-parse 
@@ -45,8 +39,7 @@
     (quasisyntax/loc stx
       (literal #'#,stx 'sym 
                (syntax-parameterize ([top (make-rename-transformer #'literal-top)]
-                                     [datum (make-rename-transformer #'literal-datum)]
-                                     [unquote (make-rename-transformer #'literal-unquote)])
+                                     [datum (make-rename-transformer #'literal-datum)])
                                     (list e ...))))]))
 
 (define-syntax (->simple-clause stx)
@@ -84,5 +77,4 @@
          #%top-interaction
          #%module-begin
          ! ~ ?
-         :- =
-         unquote)
+         :- =)

collects/tests/datalog/paren-examples/ancestor.rkt

@@ -1,12 +1,12 @@
 #lang datalog/sexp
 ; Equality test
-(! (:- (ancestor ,A ,B)
-       (parent ,A ,B)))
-(! (:- (ancestor ,A ,B)
-       (parent ,A ,C)
+(! (:- (ancestor A B)
+       (parent A B)))
+(! (:- (ancestor A B)
+       (parent A C)
        (= D C) ; Unification required
-       (ancestor ,D ,B)))
+       (ancestor D B)))
 (! (parent john douglas))
 (! (parent bob john))
 (! (parent ebbon bob))
-(? (ancestor ,A ,B))
+(? (ancestor A B))

collects/tests/datalog/paren-examples/ancestor.txt

@@ -1,6 +1,6 @@
-ancestor(ebbon, douglas).
-ancestor(ebbon, john).
-ancestor(bob, douglas).
 ancestor(ebbon, bob).
 ancestor(bob, john).
 ancestor(john, douglas).
+ancestor(bob, douglas).
+ancestor(ebbon, john).
+ancestor(ebbon, douglas).

collects/tests/datalog/paren-examples/bidipath.rkt

@@ -4,12 +4,12 @@
 (! (edge b c))
 (! (edge c d))
 (! (edge d a))
-(! (:- (path ,X ,Y)
-       (edge ,X ,Y)))
-(! (:- (path ,X ,Y)
-       (edge ,X ,Z)
-       (path ,Z ,Y)))
-(! (:- (path ,X ,Y)
-       (path ,X ,Z)
-       (edge ,Z ,Y)))
-(? (path ,X ,Y))
+(! (:- (path X Y)
+       (edge X Y)))
+(! (:- (path X Y)
+       (edge X Z)
+       (path Z Y)))
+(! (:- (path X Y)
+       (path X Z)
+       (edge Z Y)))
+(? (path X Y))

collects/tests/datalog/paren-examples/laps.rkt

@@ -2,12 +2,12 @@
 ; Laps Test
 (! (contains ca store rams_couch rams))
 (! (contains rams fetch rams_couch will))
-(! (:- (contains ca fetch ,Name ,Watcher)
-       (contains ca store ,Name ,Owner)
-       (contains ,Owner fetch ,Name ,Watcher)))
+(! (:- (contains ca fetch Name Watcher)
+       (contains ca store Name Owner)
+       (contains Owner fetch Name Watcher)))
 (! (trusted ca))
-(! (:- (permit ,User ,Priv ,Name)
-       (contains ,Auth ,Priv ,Name ,User)
-       (trusted ,Auth)))
-(? (permit ,User ,Priv ,Name))
+(! (:- (permit User Priv Name)
+       (contains Auth Priv Name User)
+       (trusted Auth)))
+(? (permit User Priv Name))
 

collects/tests/datalog/paren-examples/path.rkt

@@ -4,9 +4,9 @@
 (! (edge b c))
 (! (edge c d))
 (! (edge d a))
-(! (:- (path ,X ,Y)
-       (edge ,X ,Y)))
-(! (:- (path ,X ,Y)
-       (edge ,X ,Z)
-       (path ,Z ,Y)))
-(? (path ,X ,Y))
+(! (:- (path X Y)
+       (edge X Y)))
+(! (:- (path X Y)
+       (edge X Z)
+       (path Z Y)))
+(? (path X Y))

collects/tests/datalog/paren-examples/pq.rkt

@@ -1,8 +1,8 @@
 #lang datalog/sexp
 ; p q test from Chen & Warren
-(! (:- (q ,X)
-       (p ,X)))
+(! (:- (q X)
+       (p X)))
 (! (q a))
-(! (:- (p ,X)
-       (q ,X)))
-(? (q ,X))
+(! (:- (p X)
+       (q X)))
+(? (q X))

collects/tests/datalog/paren-examples/revpath.rkt

@@ -4,9 +4,9 @@
 (! (edge b c))
 (! (edge c d))
 (! (edge d a))
-(! (:- (path ,X ,Y)
-       (edge ,X ,Y)))
-(! (:- (path ,X ,Y)
-       (path ,X ,Z)
-       (edge ,Z ,Y)))
-(? (path ,X ,Y))
+(! (:- (path X Y)
+       (edge X Y)))
+(! (:- (path X Y)
+       (path X Z)
+       (edge Z Y)))
+(? (path X Y))

collects/tests/datalog/paren-examples/says.rkt

@@ -1,7 +1,7 @@
 #lang datalog/sexp
 (! (tpme tpme1))
 (! (ms m1 "TPME" tpme1 ek tp))
-(! (:- (says ,TPME ,M)
-       (tpme ,TPME)
-       (ms ,M "TPME" ,TPME ,A ,B)))
-(? (says ,A ,B))
+(! (:- (says TPME M)
+       (tpme TPME)
+       (ms M "TPME" TPME A B)))
+(? (says A B))

collects/tests/datalog/paren-examples/tutorial.rkt

@@ -6,23 +6,23 @@
 
 (! (parent bob john))
 (! (parent ebbon bob))
-(? (parent ,A ,B))
+(? (parent A B))
 
-(? (parent john ,B))
+(? (parent john B))
 
-(? (parent ,A ,A))
+(? (parent A A))
 
-(! (:- (ancestor ,A ,B)
-       (parent ,A ,B)))
-(! (:- (ancestor ,A ,B)
-       (parent ,A ,C)
-       (ancestor ,C ,B)))
-(? (ancestor ,A ,B))
+(! (:- (ancestor A B)
+       (parent A B)))
+(! (:- (ancestor A B)
+       (parent A C)
+       (ancestor C B)))
+(? (ancestor A B))
 
-(? (ancestor ,X john))
+(? (ancestor X john))
 
 (~ (parent bob john))
 
-(? (parent ,A ,B))
+(? (parent A B))
 
-(? (ancestor ,A ,B))
+(? (ancestor A B))