# \[ANN\] json-data-encoding 0.9

**URL:** <https://discuss.ocaml.org/t/ann-json-data-encoding-0-9/7157>\
**Category:** Community\
**Created:** [January 25, 2021, 11:23am UTC](https://discuss.ocaml.org/t/ann-json-data-encoding-0-9/7157 "2021-01-25T11:23:09Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![raphael-proust](https://sea2.discourse-cdn.com/flex020/user_avatar/discuss.ocaml.org/raphael-proust/32/415_2.png) [@raphael-proust](https://discuss.ocaml.org/u/raphael-proust)\
**Post date:** [January 25, 2021, 11:23am UTC](https://discuss.ocaml.org/t/ann-json-data-encoding-0-9/7157/1 "2021-01-25T11:23:09Z")

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On behalf of [Nomadic Labs](https://nomadic-labs.com/), I’m happy to announce the release of json-data-encoding version 0.9.

The code is hosted on Gitlab: [Nomadic Labs / json-data-encoding · GitLab](https://gitlab.com/nomadic-labs/json-data-encoding)  
It is distributed under GNU LGPL with linking exception.  
The documentation is available online: [index](https://nomadic-labs.gitlab.io/json-data-encoding/)  
The package is available under opam: `opam install json-data-encoding`

json-data-encoding is a library to define encoder/decoder values to translate OCaml values to JSON and back. It also generates JSON schemas so you can document the value representation. It can use either Ezjsonm or Yojson as backends.

The version 0.9 has the following new features:

- more tests
- memoisation of fixpoint encoding to avoid repeated computations
- support for `format` field for string schemas (see [string — Understanding JSON Schema 7.0 documentation](https://json-schema.org/understanding-json-schema/reference/string.html#format)) (contributed by @levillain.maxime)
- fixed integer bound printing in schemas (bug report by @pw374)
- support for json-lexeme streaming (see details below)
- support for inclusion/exclusion of default-value fields during serialisation (contributed by @levillain.maxime)
- improved union-of-object schemas (contributed by @levillain.maxime)

One major difference with the previous release is the inclusion of a lexeme-streaming JSON constructor. Specifically, the function

```auto
val construct_seq : 't encoding -> 't -> jsonm_lexeme Stdlib.Seq.t

```

generates a sequence of `Jsonm.lexeme` (the . This sequence is lazy (in the sense of `Stdlib.Seq` not of `Stdlib.Lazy`) and it paves the way to a similar feature in `data-encoding`. An interesting feature of sequences is that they can be used in Vanilla OCaml settings as well as Lwt/Async settings where they allow user-driven yielding in between elements.

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<div class="post-metadata">

**Author:** ![raphael-proust](https://sea2.discourse-cdn.com/flex020/user_avatar/discuss.ocaml.org/raphael-proust/32/415_2.png) [@raphael-proust](https://discuss.ocaml.org/u/raphael-proust)\
**Post date:** [January 29, 2021, 11:19am UTC](https://discuss.ocaml.org/t/ann-json-data-encoding-0-9/7157/2 "2021-01-29T11:19:11Z")

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On behalf of Nomadic Labs, it is my pleasure to release json-data-encoding.0.9.1. The code of this packaging-fix release is identical to the recent json-data-encoding.0.9 but the license information has been corrected.

The previous release had _LGPL with linking exception_ headers in the source files, LICENSE file in the repository, and license field in the opam file. However, the code was actually under MIT as per agreement of the copyright holders. Release 0.9.1 has the correct license headers, LICENSE file and license field in the opam files.

The code of 0.9/0.9.1 is in dual license. Future releases will be under MIT license only.