A Haskell implementation of the current [JSON Schema](http://json-schema.org/) specification (Draft 4).
[Hackage](https://hackage.haskell.org/package/hjsonschema) / [GitHub](https://github.com/seagreen/hjsonschema) / [Travis CI](https://travis-ci.org/seagreen/hjsonschema)
NOTE: You currently CANNOT use untrusted JSON data to make schemas. Schemas with circular references can cause infinite loops. This is being addressed: see the issue list.
# Example
See [Example.hs on GitHub](https://github.com/seagreen/hjsonschema/blob/master/Example.hs).
# Tests
## Install
`git submodule update --init`
## Run
Will run self-contained:
`cabal test local`
Will start an HTTP server temporarily on port 1234:
`cabal test remote`
# Details
## Goals
+ Be a correct and fast implementation of the spec.
+ Be a useful reference for implementers in other languages. Haskell's high level nature, expressive type system and referential transparency suit this purpose well.
## Good Parts
+ Passes all the tests in the [language agnostic test suite](https://github.com/json-schema/JSON-Schema-Test-Suite).
+ Very modular, which should make it easy to support future versions of the specification.
## Bad Parts
+ Uses the [regexpr](https://hackage.haskell.org/package/regexpr-0.5.4) regular expression library for the "pattern" validator. It should use a library based on the ECMA 262 regex dialect, which the [spec](http://json-schema.org/latest/json-schema-validation.html#anchor33) requires.
## Notes
+ `draft4.json` is from commit # cc8ec81ce0abe2385ebd6c2a6f2d6deb646f874a [here](https://github.com/json-schema/json-schema).
## Credits
[TJ Weigel](http://tjweigel.com/) created the logo.
[Tim Baumann](https://github.com/timjb) wrote [aeson-schema](https://hackage.haskell.org/package/aeson-schema), on which hjsonschema's test code and its implementation of `SchemaGraph` were based.
[Julian Berman](https://github.com/Julian) maintains the fantastic [language agnostic test suite](https://github.com/json-schema/JSON-Schema-Test-Suite).