rs: Add read-ctx and illustrate it in example.org.

example/example.org

@@ -519,6 +519,22 @@ tab
    - a
    - b
 
+   You can also give a name to a list and read it with =munch-sexp=:
+
+   #+NAME: ctx1
+   - x y
+   - z
+   -
+   - t
+
+   #+BEGIN_SRC racket :results output drawer :var input-ctx=munch-sexp(ctx1)
+(read-ctx input-ctx)
+   #+END_SRC
+
+   #+RESULTS:
+   :RESULTS:
+   (list (set 'x 'y) (set 'z) (set) (set 't))
+   :END:
 
 * Local Variables                                                  :noexport:
   # Local Variables:

rs.rkt

@@ -31,7 +31,7 @@
  ;; Contracts
  (contract-out [reaction-system/c contract?])
  ;; Syntax
- unorg-rs org-rs)
+ unorg-rs org-rs read-ctx)
 
 ;;; =================
 ;;; Basic definitions
@@ -107,6 +107,9 @@
 (define (read-context-sequence str)
   (map (compose list->set read-symbol-list) (flatten (read-org-sexp str))))
 
+;;; A shortcut to read-context-sequence.
+(define-syntax-rule (read-ctx str) (read-context-sequence str))
+
 ;;; Removes the first and the last symbol of a given string.
 (define (drop-first-last str)
   (substring str 1 (- (string-length str) 1)))