Define `any' signature differently.

... to actually enable the subtyping check.  Also, make named
signatures work for signature variables.

collects/deinprogramm/DMdA.rkt

@@ -921,8 +921,8 @@
 (define symbol (signature/arbitrary arbitrary-symbol (predicate symbol?)))
 (define empty-list (signature (one-of empty)))
 
-(define unspecific (signature (predicate (lambda (_) #t))))
-(define any (signature (predicate (lambda (_) #t))))
+(define unspecific (signature unspecific %unspecific))
+(define any (signature any %any))
 
 ;; aus collects/lang/private/teach.ss
 

collects/deinprogramm/signature/signature-syntax.rkt

@@ -94,10 +94,10 @@
     (?id
      (identifier? #'?id)
      (with-syntax ((?stx (phase-lift stx))
-		   (?name name))
+		   (?name (or name (syntax->datum #'?id))))
        (let ((name (symbol->string (syntax->datum #'?id))))
 	 (if (char=? #\% (string-ref name 0))
-	     #'(make-type-variable-signature '?id ?stx)
+	     #'(make-type-variable-signature '?name ?stx)
 	     (with-syntax
 		 ((?raise
 		   (syntax/loc #'?stx

collects/lang/private/signature-syntax.rkt

@@ -85,10 +85,10 @@
     (?id
      (identifier? #'?id)
      (with-syntax ((?stx (phase-lift stx))
-		   (?name name))
+		   (?name (or name (syntax->datum #'?id))))
        (let ((name (symbol->string (syntax->datum #'?id))))
 	 (if (char=? #\% (string-ref name 0))
-	     #'(make-type-variable-signature '?id ?stx)
+	     #'(make-type-variable-signature '?name ?stx)
 	     (with-syntax
 		 ((?raise
                    #'(error 'signatures "expected a signature, found ~e" ?id)))

collects/lang/private/teach.rkt

@@ -2916,9 +2916,9 @@
 (define Symbol (signature/arbitrary arbitrary-symbol (predicate symbol?)))
 (define Empty-list (signature (one-of empty)))
 
-(define Any (signature (predicate (lambda (_) #t))))
+(define Any (signature Any %Any))
 
-(define Unspecific (signature (predicate (lambda (_) #t))))
+(define Unspecific (signature Unspecific %Unspecific))
 
 (define (cons-of car-sig cdr-sig)
   (make-pair-signature #t car-sig cdr-sig))