add contracts

beautiful-racket/br/demo/jsonic-2/reader.rkt

@@ -1,6 +1,10 @@
 #lang br/quicklang
 (require "tokenizer.rkt" "parser.rkt")
-(define (read-syntax path port)
+(define (syntax-no-bindings? stx)
+  (and (syntax? stx)
+       (equal? stx (strip-bindings stx))))
+(define/contract (read-syntax path port)
+  (path? input-port? . -> . syntax?)
   (define parse-tree (parse path (tokenize port)))
   (define module-datum `(module jsonic-module br/demo/jsonic/expander
                           ,parse-tree))

beautiful-racket/br/demo/jsonic-2/tokenizer.rkt

@@ -1,7 +1,13 @@
 #lang br/quicklang
 (require brag/support)
-(define (tokenize port)
-  (define (next-token)
+
+(define (token? x)
+  (or (eof-object? x) (string? x) (token-struct? x)))
+
+(define/contract (tokenize port)
+  (input-port? . -> . (-> token?))
+  (define/contract (next-token)
+    (-> token?)
     (define our-lexer
       (lexer
        [(eof) eof]