Add cons' and cons?' as synonyms for make-pair' and pair?' to DMdA.

Requested by Michael Hanus & Peter Thiemann.

collects/deinprogramm/DMdA-beginner.rkt

@@ -15,7 +15,7 @@
  (all-from-except beginner: deinprogramm/DMdA procedures
 		  set! define-record-procedures-2 eq? equal?
 		  quote
-		  make-pair pair? first rest
+		  make-pair pair? cons? first rest
 		  length map for-each reverse append list list-ref fold
 		  symbol? string->symbol symbol->string
 		  apply))

collects/deinprogramm/DMdA.rkt

@@ -25,8 +25,6 @@
 
 (provide provide lib planet rename-out require #%datum #%module-begin #%top-interaction) ; so we can use this as a language
 
-(provide cons) ; hack, for the stepper
-
 (provide (all-from-out deinprogramm/define-record-procedures))
 (provide (all-from-out test-engine/scheme-tests))
 (provide signature define-contract :
@@ -246,8 +244,12 @@
   (empty list "die leere Liste")
   (make-pair (%a (list %a) -> (list %a))
 	     "erzeuge ein Paar aus Element und Liste")
+  ((DMdA-cons cons) (%a -> boolean)
+	     "erzeuge ein Paar aus Element und Liste")
   (pair? (%a -> boolean)
 	 "feststellen, ob ein Wert ein Paar ist")	
+  (cons? (%a -> boolean)
+	 "feststellen, ob ein Wert ein Paar ist")
   (empty? (%a -> boolean)
 	  "feststellen, ob ein Wert die leere Liste ist")
   
@@ -389,6 +391,12 @@
 (define (empty? obj)
   (null? obj))
 
+(define (cons? obj)
+  (pair? obj))
+
+(define (DMdA-cons f r)
+  (make-pair f r))
+
 (define (DMdA-append . args)
   (let loop ((args args)
 	     (seen-rev '()))