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Why is there no support for serializing seq<'T> to JSON
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From http://www.websharper.com/docs/json:

Collections

Values of type list<'T>, 'T[] and Set<'T> are represented as JSON arrays:

Content.Json [|"a string"; "another string"|]

// Output: ["a string", "another string"]

Content.Json (Set ["a string"; "another string"])

// Output: ["another string", "a string"]

Why doesn't Content.Json support seq<'T>? I know that I can use Array.OfSeq to get the effect, but this would require an additional memory copy that I would like to avoid. As is, I would like to use Content.Json, but I end up having to write my own JSON serializers due to the lack of an extension API.

Additionally, are there any serious blockers to adding an extension API, or is it simplying a question of defining one and putting in the effort to write one?

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One simple reason is that seq<'T> is lazy.

By on 5/2/2016 3:04 AM ()

I am fine with the result being non-lazy; that is, Content.Json iterates over the seq<'T> and generates a JSON list of 'T Json. That would be the preferred behavior because then my backend code can return seq<'T> types that do all sort of useful things (e.g. iterate over a flatten seq of a subsequences) Does F# have some limitation with type reflection or duck typing that prevents this, or is this breaking some design guideline.

A second feature request would be to support an interface type for custom JSON representations something like

type IJsonSerialize = interface abstract ToJSON : unit -> string end

If there isn't any serious reason why it couldn't be supported, I can start to look through the code base and see if something can be prototyped to suit my needs.

By on 5/2/2016 4:05 PM ()

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