https://github.com/uswitch/ej

a tool to convert from EDN to JSON
https://github.com/uswitch/ej

Last synced: 11 months ago
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a tool to convert from EDN to JSON

• Host: GitHub
• URL: https://github.com/uswitch/ej
• Owner: uswitch
• License: bsd-2-clause
• Created: 2014-12-02T16:40:49.000Z (over 11 years ago)
• Default Branch: master
• Last Pushed: 2017-05-08T14:39:35.000Z (about 9 years ago)
• Last Synced: 2024-04-14T11:59:46.985Z (about 2 years ago)
• Language: Haskell
• Size: 5.86 KB
• Stars: 16
• Watchers: 53
• Forks: 2
• Open Issues: 0
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

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README

          
# ej

A tool to convert from EDN to JSON.

## Usage

    $ ej < some.edn > some.json

Note: no command line options (or even filenames) are (currently) accepted.

Output is one record per line.

    $ cat drinks.edn

    {:name "milkshake" :sizes [330 500 1000] :contents {:milk true :alcohol false}}

    {:name "latte" :sizes [125 250] :contents {:milk true :alcohol false}}

    {:name "beer" :sizes [284 568] :contents {:milk false :alcohol true}}

    {:name "white russian" :sizes [100] :contents {:milk true :alcohol true}}

    {:name "water" :sizes [1000] :contents {:milk false :alcohol false}}

    $ ej < drinks.edn

    {"contents":{"alcohol":false,"milk":true},"name":"milkshake","sizes":[330,500,1000]}

    {"contents":{"alcohol":false,"milk":true},"name":"latte","sizes":[125,250]}

    {"contents":{"alcohol":true,"milk":false},"name":"beer","sizes":[284,568]}

    {"contents":{"alcohol":true,"milk":true},"name":"white russian","sizes":[100]}

    {"contents":{"alcohol":false,"milk":false},"name":"water","sizes":[1000]}

### jq

ej works well with [jq](http://stedolan.github.io/jq), a tool for command-line JSON processing.

To get pretty JSON from EDN:

    $ ej < some.edn | jq .

To query EDN from the command line:

    $ cat drinks.edn | ej | jq -r 'select(.contents.milk) | .name'

    milkshake

    latte

    white russian

## Caveats

* EDN tagging information is removed

* Rational numbers are parsed, and become floats in JSON (the EDN spec doesn't mention rationals, but it looks as if it should)

* keywords and symbols as map keys become strings

* other types used as map keys become JSON-encoded strings

## Prerequisites

* The Haskell Stack

    $ curl -sSL https://get.haskellstack.org/ | sh

(Be prepared for a wait)

## Installation

    $ git clone https://github.com/uswitch/ej.git

    $ cd ej

    $ stack setup

    $ stack install

which, if all goes well, will create `~/.local/bin/ej`. It may be a

good idea to put `~/.local/bin` in your `PATH`.

## Motivation

* Needed a fast way to convert streams of EDN to JSON, to get benefit of tools such as jq.

* Clojure takes too long to start for a command line tool.

* There's a Go implementation, but its licence is unclear.

* I'm a Haskell beginner, so I thought this would make a good first (useful) project.