use `contract-out` instead of `define/contract`

beautiful-racket-demo/jsonic-demo-2/colorer.rkt

@@ -3,13 +3,7 @@
 
 (define in-racket-expr? #f)
 
-(define/contract (color-jsonic port)
-  (input-port? . -> . (values
-                       (or/c string? eof-object?)
-                       symbol?
-                       (or/c symbol? #f)
-                       (or/c exact-positive-integer? #f)
-                       (or/c exact-positive-integer? #f)))
+(define (color-jsonic port)
   (define jsonic-lexer
     (lexer
      [(eof) (values lexeme 'eof #f #f #f)]
@@ -31,7 +25,15 @@
            (not (equal? (peek-string 2 0 port) "$@")))
       (racket-lexer port)
       (jsonic-lexer port)))
-(provide color-jsonic)
+(provide
+ (contract-out
+  [color-jsonic
+   (input-port? . -> . (values
+                        (or/c string? eof-object?)
+                        symbol?
+                        (or/c symbol? #f)
+                        (or/c exact-positive-integer? #f)
+                        (or/c exact-positive-integer? #f)))]))
 
 (module+ test
   (require rackunit)

beautiful-racket-demo/jsonic-demo-2/indenter.rkt

@@ -1,14 +1,11 @@
 #lang br
-(require br/indent racket/gui/base racket/contract)
-(provide indent-jsonic)
+(require br/indent racket/contract racket/gui/base)
 
 (define indent-width 2)
 (define (left-bracket? c) (member c (list #\{ #\[)))
 (define (right-bracket? c) (member c (list #\} #\])))
 
-(define/contract (indent-jsonic tbox [posn 0])
-  ((is-a?/c text%) exact-nonnegative-integer?  . -> .
-                   (or/c exact-nonnegative-integer? #f))
+(define (indent-jsonic tbox [posn 0])
   (define prev-line (previous-line tbox posn))
   (define current-line (line tbox posn))
   (define prev-indent (or (line-indent tbox prev-line) 0))
@@ -22,6 +19,11 @@
        (- prev-indent indent-width)]
       [else prev-indent]))
   (and (exact-positive-integer? current-indent) current-indent))
+(provide
+ (contract-out
+  [indent-jsonic (((is-a?/c text%)) 
+                  (exact-nonnegative-integer?) . ->* .
+                  (or/c exact-nonnegative-integer? #f))]))
 
 (module+ test
   (require rackunit)

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

@@ -1,10 +1,10 @@
 #lang br/quicklang
 (require "tokenizer.rkt" "parser.rkt" racket/contract)
 
-(define/contract (read-syntax path port)
-  (any/c input-port? . -> . syntax?)
+(define (read-syntax path port)
   (define parse-tree (parse path (tokenize port)))
   (define module-datum `(module jsonic-module jsonic-demo-2/expander
                           ,parse-tree))
   (datum->syntax #f module-datum))
-(provide read-syntax)
+(provide (contract-out
+          [read-syntax (any/c input-port? . -> . syntax?)]))

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

@@ -13,11 +13,9 @@
   (check-true (token? (token 'A-TOKEN-STRUCT "hi")))
   (check-false (token? 42)))
 
-(define/contract (tokenize port)
-  (input-port? . -> . (-> token?))
+(define (tokenize port)
   (port-count-lines! port)
-  (define/contract (next-token)
-    (-> token?)
+  (define (next-token)
     (define our-lexer
       (lexer
        [(eof) eof]
@@ -37,7 +35,8 @@
                                   (pos lexeme-start)))]))
     (our-lexer port))
   next-token)
-(provide tokenize)
+(provide (contract-out
+          [tokenize (input-port? . -> . (-> token?))]))
 
 (module+ test
   (check-equal? (apply-tokenizer tokenize "// comment\n") empty)