Stupid / simple JSON command line processing with Ruby

README.md

Based on an example for Elvish.

From comment posted to HN:

I love the structured pipes, but as mentioned in another discussion, replacing the shell is a big leap for a lot of people. And you can get quite far without it with tools like "jq". And when I saw this, I just had to tinker a bit to see what I could do with Ruby, based on the example on the homepage:

$ curl -s https://api.github.com/repos/elves/elvish/issues | jr 'each{|issue| puts "#{issue["number"]}: #{issue["title"]}"} ' | head -n 11

Or (I expect pitchforks when you see the implementation for this):

$ curl -s https://api.github.com/repos/elves/elvish/issues | puts{"#{$I["number"]}: #{$I["title"]}"}' | head -n 11

$J holds the full JSON. $I holds each item processed via #each or any method in Enumerable built on top of each, if you really want to make things brief.

This also lets you process a file. E.g. if you've redirected the curl to "/tmp/elves.json", you can do "jr /tmp/elves.json 'puts{$I["title"]}'

jr

#!/usr/bin/ruby

require 'json'

script = ARGV.pop

$J = JSON.parse(ARGF.read)

# I'm going to burn in hell for this. These let you use all of
# Enumerable on the main object, so you can e.g. call "each",
# "collect" etc. without a receiver. This is not good practice
# in a bigger app..

include Enumerable

def each █
  $J.each{|i| $I = i; block.call(i)}
end

def puts *args, &block
  args << collect(&block)
  Kernel.puts(*args)
end

eval(script)

You can further simplify by doing this:

    def each █
       $J.each do |i|
         $I = i;
         i.keys.each {|k| eval("$#{k} = $I[k].to_s")}
         block.call(i)
       end
     end

Which lets you do:

    jr 'puts{$number+": "+$title}'

(Warning: will happily clobber pre-defined globals, like $stdin; don't use on data users can manipulate the keys of)