Relax top-level restriction of parseJSON

[matil019]

As described in the fregedoc, parseJSON fails if it is decoding a string neither into an object nor an array:

import frege.data.JSON

main = println $ (parseJSON "true" :: Maybe Bool)
-- prints "Nothing"

However, since Bool is an instance of FromJSON it's misleading.

It's true that any valid JSON should have an object or an array as its top-level entity. However, I think it's applications' responsibility to check the validity of a JSON, and the implementation of the library should be consistent to its type.

[talios]

On 6 Aug 2018, at 0:26, matil019 wrote: It's true that any valid JSON should have an object or an array as its top-level entity. However, I think it's applications' responsibility to check the validity of a JSON, and the implementation of the library should be consistent to its type.

Actually, `true` IS valid JSON. As is `"Hello World"`, even `42` is valid JSON. Or more, they are valid representations of JSON Values.

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