improve contracts

beautiful-racket-lib/br/indent.rkt

@@ -16,7 +16,7 @@
 (define indent-width 2)
 
 (define/contract (char text pos)
-  ((is-a?/c text%) exact-nonnegative-integer? . -> . char?)
+  ((is-a?/c text%) (or/c exact-nonnegative-integer? #f) . -> . (or/c char? #f))
   (and pos (send text get-character pos)))
 
 (module+ test
@@ -77,11 +77,11 @@
   (check-equal? (next-line t 11) #f))
 
 (define/contract (valid-line? text line)
-  ((is-a?/c text%) exact-nonnegative-integer? . -> . boolean?)
+  ((is-a?/c text%) (or/c exact-nonnegative-integer? #f) . -> . boolean?)
   (and line (<= 0 line (send text last-line))))
 
 (define/contract (line-start text line)
-  ((is-a?/c text%) exact-nonnegative-integer? . -> . (or/c exact-nonnegative-integer? #f))
+  ((is-a?/c text%) (or/c exact-nonnegative-integer? #f) . -> . (or/c exact-nonnegative-integer? #f))
   (and (valid-line? text line)
        (send text line-start-position line)))
 
@@ -92,7 +92,7 @@
   (check-equal? (line-start t 3) #f))
   
 (define/contract (line-end text line)
-  ((is-a?/c text%) exact-nonnegative-integer? . -> . (or/c exact-nonnegative-integer? #f))
+  ((is-a?/c text%) (or/c exact-nonnegative-integer? #f) . -> . (or/c exact-nonnegative-integer? #f))
   (and (valid-line? text line)
        (send text line-end-position line)))
 
@@ -110,7 +110,7 @@
               pos))
 
 (define/contract (line-start-visible text line)
-  ((is-a?/c text%) exact-nonnegative-integer? . -> . (or/c exact-nonnegative-integer? #f))
+  ((is-a?/c text%) (or/c exact-nonnegative-integer? #f) . -> . (or/c exact-nonnegative-integer? #f))
   (define start (line-start text line))
   (define end (line-end text line))
   (and start end (first-visible-char-pos text start end)))
@@ -122,7 +122,7 @@
   (check-equal? (line-start-visible t 3) #f))
 
 (define/contract (line-end-visible text line)
-  ((is-a?/c text%) exact-nonnegative-integer? . -> . (or/c exact-nonnegative-integer? #f))
+  ((is-a?/c text%) (or/c exact-nonnegative-integer? #f) . -> . (or/c exact-nonnegative-integer? #f))
   (define start+1 (line-end text line)) ; start before newline
   (define end+1 (line-start text line))
   (and start+1 end+1 (first-visible-char-pos text (sub1 start+1) (sub1 end+1))))
@@ -134,7 +134,7 @@
   (check-equal? (line-end-visible t 3) #f))
 
 (define/contract (line-indent text line)
-  ((is-a?/c text%) exact-nonnegative-integer? . -> . (or/c exact-nonnegative-integer? #f))
+  ((is-a?/c text%) (or/c exact-nonnegative-integer? #f) . -> . (or/c exact-nonnegative-integer? #f))
   (and (valid-line? text line)
        (let ([lsv (line-start-visible text line)])
          (and lsv ; could be #f

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

@@ -1,5 +1,5 @@
 #lang br
-(require br/indent)
+(require br/indent racket/gui/base)
 (provide indent-jsonic)
 
 (define indent-width 2)
@@ -10,9 +10,11 @@
 ;; if this line begins with } or ], outdent.
 ;; if last line begins with { or [, indent.
 ;; otherwise use previous indent
-(define (indent-jsonic textbox [pos 0])
-  (define this-line (line textbox pos))
-  (define prev-line (previous-line textbox pos))
+(define/contract (indent-jsonic textbox [tbpos 0])
+  ((is-a?/c text%) exact-nonnegative-integer?  . -> .
+                   (or/c exact-nonnegative-integer? #f))
+  (define this-line (line textbox tbpos))
+  (define prev-line (previous-line textbox tbpos))
   (define prev-indent (or (line-indent textbox prev-line) 0))
   (define this-indent
     (cond
@@ -28,14 +30,16 @@
   (define test-str #<<here
 #lang br/demo/jsonic
 {
-"string": @$(string-append "foo" "bar")$@,
+"value",
+"string":
+[
 {
 "array": @$(range 5)$@,
-"object": @$(hash "k1" "valstring" (format "~a" 42) (hash "k1" (range 10) "k2" 42))$@
+"object": @$(hash 'k1 "valstring")$@
 }
-// "bar" :
+]
+// "bar"
 }
 here
     )
-  (check-equal? (string-indents (apply-indenter indent-jsonic test-str))
-                (map (λ(x) (* x indent-width)) '(0 0 1 1 2 2 1 1 0))))
+  (display (apply-indenter indent-jsonic test-str)))