crap_json

A crap JSON dumper for Erlang. Takes some liberties. Reasonably tested. Test cases use PropEr. Requires Erlang R16 or greater.

         

Current Library Status: Usable

This library is considered to be production level correct, but is probably not production level fast.

Improvements will be gladly accepted.

K what's this nonsense

I needed a json dumper for a thing a friend and I were doing with htstub. It didn't have to be fancy. It was export to JS only; no need to parse. It did have to work reliably, to express JS primitives, to express nesting, and to work with international text. I did not need the expression of Erlang exotic types like references and PIDs.

Thus (choral music) another piece o' crap was born.

This library is not intended to convert all Erlang terms to JSON. It makes no attempt to handle references, ports, PIDs, e17 maps, et cetera.

This library is only intended to provide an export point for JSON which covers all of JSON. If you want to say something that JSON can say, this library has a single well defined notation in Erlang terms that can support you. Also, I hope that you find that notation brief and convenient.

Usage

For detailed usage see the docs that I probably haven't written yet.

Text

1> crap_json:to_json("a").
<<"\"a\"">>

2> crap_json:to_json("abc def").
<<"\"abc def\"">>

3> crap_json:to_json("abc \r \n def").
<<"\"abc \\r \\n def\"">>

4> crap_json:to_json("汉语").
<<"\"\\u6C49\\u8BED\"">>

Numbers

5> crap_json:to_json(1).
<<"1">>

6> crap_json:to_json(-1).
<<"-1">>

7> crap_json:to_json(-2.5).
<<"-2.5">>

8> crap_json:to_json(0.1).      % good handling of rounding error
<<"0.1">>

Atoms as JS keywords

9> crap_json:to_json(true).
<<"true">>

10> crap_json:to_json(false).
<<"false">>

11> crap_json:to_json(null). 
<<"null">>

(This list used to contain undefined, because the encoder used to handle it. That's not correct; despite being a JS keyword, JSON doesn't have it. Removed. Thanks, Gocy.)

Proplists as Objects

12> io:format("~s~n", [crap_json:to_json( [ {"height", "2in"}, {"width", "3in"} ]) ]).
{"height":"2in","width":"3in"}

13> io:format("~s~n", [
  crap_json:to_json( [ 
    {"name","James Bond"}, 
    {"powers", [ 
      {"sharpshooter", 5}, 
      {"drive", 4} 
    ]}, 
    { "realname", undefined }, 
    { "license to kill", true } 
  ]) 
]). 
{"name":"James Bond","powers":{"sharpshooter":5,"drive":4},"realname":undefined,"license to kill":true}

... the latter of which Chrome Debugger parses thusly:

Tuples as Arrays

14> crap_json:to_json( {1,2,3} ).
<<"[1,2,3]">>

15> crap_json:to_json( {1, {2,3}, {true,false,null} } ).
<<"[1,[2,3],[true,false,null]]">>

The Verdict

Okay, so how's it look?

The Good

• Reasonably well tested, including stochastic tests from PropEr
• Tolerably documented
• Adequate

The Bad

• Dump only; no parse
• Probably could be a lot faster
• Not entirely finished as of this writing

The Ugly

• Probably can't be made round-trip parse stable because of collisions like how binaries are handled
• Very new; may still have lurking bugs or dumb mistakes

Polemic

crap_json is MIT licensed, because viral licenses and newspeak language modification are evil. Free is only free when it's free for everyone.