Function to Check if string is JSON object

It's also an example of a customized SystemFunction extension (ZZISJSON) in Caché & IRIS
This time it is to be included in %ZLANGF00.mac

A JSON string is mostly imported from a file or over REST
You rely on a clean and compatible structure. This is the check.

required: ZPretty.mac

demo

USER>ZWRITE jsn  
jsn="{"Name":"Li,Robert K.","SSN":"672-92-9664","DOB":"1975-01-12","Home":{"Street":"986 Washington Blvd","City":"Boston","State":"PA","Zip":"95802"},"Office":{"Street":"6012 First Place","City":"Reston","State":"MT","Zip":"77739"},"Spouse":{"Name":"Avery,Zelda H.","SSN":"323-13-7437","DOB":"1943-03-27","Home":{"Street":"196 Main Drive","City":"Youngstown","State":"WY","Zip":"53229"},"Office":{"Street":"4056 Franklin Court","City":"Bensonhurst","State":"IA","Zip":"27688"},"FavoriteColors":["Black"],"Age":77},"Age":45,"Title":"Associate Marketing Manager","Salary":10421}" 

USER>if $ZZISJSON(jsn) write "OK"
OK

USER>set is(1)=$ZZISJSON(jsn),is(2)=$ZZISJSON(jsn_",home:") zwrite is
is(1)=1
is(2)=0

GitHub