# HG changeset patch
# User Chris Cannam
# Date 1619075512 -3600
#      Thu Apr 22 08:11:52 2021 +0100
# Node ID 7d75cf1278cf3dce73d74406033e84db20e1de30
# Parent  ae04bfe3da886b0678223c488b162fe1dc9652dd
Write integers as integers

diff --git a/json.sml b/json.sml
--- a/json.sml
+++ b/json.sml
@@ -366,7 +366,16 @@
         in
             implode (escape' [] (explode s))
         end
-        
+
+    fun serialiseNumber n =
+        implode (map (fn #"~" => #"-" | c => c)
+                     (explode
+                          (if Real.isFinite n andalso
+                              Real.== (n, Real.realRound n) andalso
+                              Real.<= (Real.abs n, 1e6)
+                           then Int.toString (Real.round n)
+                           else Real.toString n)))
+            
     fun serialise json =
         case json of
             OBJECT pp => "{" ^ String.concatWith
@@ -375,8 +384,7 @@
                                                 serialise value) pp) ^
                          "}"
           | ARRAY arr => "[" ^ String.concatWith "," (map serialise arr) ^ "]"
-          | NUMBER n => implode (map (fn #"~" => #"-" | c => c) 
-                                     (explode (Real.toString n)))
+          | NUMBER n => serialiseNumber n
           | STRING s => "\"" ^ stringEscape s ^ "\""
           | BOOL b => Bool.toString b
           | NULL => "null"