Use CJSON to read JSON

Profiling shows that most time is spent in:

- medea#read-json
- chicken.port#with-input-from-string

Use the cjson egg to read JSON to go a lot faster.

Note that we still write JSON using medea; that's not slow.

Thanks to wasamasa and sjamaan on #chicken for profiling tips.

pandoc.egg

@@ -8,7 +8,7 @@
  (license "MIT")
  (author "Lassi Kortela")
  (maintainer "Lassi Kortela")
- (dependencies http-client medea scsh-process)
+ (dependencies cjson http-client medea scsh-process)
  (test-dependencies)
  (distribution-files
   "pandoc.server.chicken.scm"

pandoc.server.chicken.scm

@@ -8,6 +8,7 @@
 
   (import (scheme)
           (chicken base)
+          (cjson)
           (only (chicken port) with-input-from-string)
           (only (chicken io) read-string)
           (only (http-client) with-input-from-request)
@@ -37,9 +38,17 @@
                         (cons 'text input-string)))
                 input-strings)))))
      (lambda ()
-       (map (lambda (string)
-              (with-input-from-string string read-json))
-            (vector->list (read-json))))))
+       (let ((array (string->cjson (read-string))))
+         (unless (eq? cjson/array (cjson-type array))
+           (error "Got unexpected JSON from pandoc-server"))
+         (let loop ((i (- (cjson-array-size array) 1)) (results '()))
+           (if (< i 0) results
+               (loop (- i 1)
+                     (cons (cjson-schemify
+                            (string->cjson
+                             (cjson-schemify
+                              (cjson-array-ref array i))))
+                           results))))))))
 
   (define (pandoc-server-files->json input-format input-filenames)
     (pandoc-server-strings->json