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JSON Parser

This parser uses Applicative and the newtype, Parser, to parse JSON.

It either succeeds or fails, returning Nothing.

Note that the newtype, Parser, as well as some of the other code within SExpr.hs and AParser.hs comes from Professor Brent Yorgey's U of Penn class.

How to Run

Prelude> :l JsonParser.hs 
[1 of 4] Compiling AParser          ( AParser.hs, interpreted )
[2 of 4] Compiling Model            ( Model.hs, interpreted )
[3 of 4] Compiling SExpr            ( SExpr.hs, interpreted )
[4 of 4] Compiling JsonParser       ( JsonParser.hs, interpreted )
Ok, modules loaded: JsonParser, SExpr, Model, AParser.
*JsonParser> runParser parseJson "[1,2,3]"
Just (JArray (Arr [Num 1.0,Num 2.0,Num 3.0]),"")

*JsonParser> runParser parseJson " { \"foo\" : \"bar\" } "
Just (JObject "foo" (fromList [S "bar"])," ")

*JsonParser> runParser parseJson " { \"foo\" : [\"bar\", true, null] } "
Just (JObject "foo" (fromList [S "bar",B True,N Null])," ")

*JsonParser> runParser parseJson " { \"foo\" : whoops "
Nothing

*JsonParser> runParser parseJson " { \"foo\" : [1,2,\"\\\" with escaped quote \\\" \"] } "
Just (JObject "foo" (fromList [Num 1.0,Num 2.0,S "\" with escaped quote \" "])," ")

TODO

  • Support all escaped characters
  • Re-factor to return error information upon a parse error
  • Test it (besides the few examples I've used so far)