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hello everyone and welcome to this short
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lightning talk
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traverse complex json structures with
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live feedback
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this is a pre-recorded talk and part of
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the e-max conf 2020 schedule
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this is what we're going to do I'll make
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a quick introduction to the topic at
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hand
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I'll give you a demonstration of some
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tools and then we'll leave you
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with the links to set tools
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before that just a little bit about me I
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am the
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ceo and co-founder of a company
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based in the swiss mountains called 200
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okay
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we are a product incubator and
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service consultancy but we like to spend
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most or at least
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as much time as we can building free
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software
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I'm also an ordained zen monk and abbott
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of the lambda zen temple
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you can reach me anytime on questions
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regarding Emacs
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for example at ala at 200ok.ch
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[Music]
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but back to the topic at hand the
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proposition is as following
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most work on the computer is based on
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either text processing or text
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consumption
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and very often the text which you need
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to process
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is in a structured format for example in
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json
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that might even be if your job is not
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programming per se
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and reading through such a bigger chunk
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of json can be non-trivial however
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while just reading and understanding it
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will be essential to getting your job
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done
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so let's quickly check out an example
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json file this is from the github api
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where which is a request sorry the
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response to a request for a specific
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issue on the github api so let's
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quickly check that one out
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okay so here it is open and we can
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already see that there is lots of stuff
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going on here
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it's uh 200 lines it's not going to be
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very easy just just to find out what are
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the top level things in here what are
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the top level attributes of course I can
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do this
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and maybe it would by hand but that
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doesn't scale
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I can use cool Emacs facilities like the
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height show mode and try to
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fold all the things that are top level
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but that also doesn't really scale
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there must be a better way and of course
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there is there is prior art
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there is a tool called jq I'm going to
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quote the usp
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from their website jq is like
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sed said for json data you can use it to
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slice and filter and map
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and transform structured data with the
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same ease that
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z awk grep and friends let you play with
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text
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let me give you a quick demonstration of
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it by the way
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it's written in portable c it has zero
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runtime dependency so it's very easy
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to get started with it and use it on
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pretty much any unix-based
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computer sorry no linux based computer
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apologies okay so let's explore a
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json file with it it's a command line
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tool and it has a very
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simple command line syntax so you
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call the binary and then you give it a
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query
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and a file and then we'll return
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its answer so for example if I want the
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top level keys
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I will just say jq keys the file and it
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will return the keys
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simple as that so let's check this out
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in a real
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shell here I am in eshel
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let's run jq keys on the github
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issue comment and we can see
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that we have actually received a list
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back here with the top level
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things okay so this issue it looks very
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very interesting so let's uh ask it to
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give me more information on this
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issue then it's hairy again that's a lot
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of stuff
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I mean lucky for for us we are in Emacs
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here so we can use nice shortcuts we can
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copy this we go can go in here just
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select that
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get that out or something like this but
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still
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this is not really it's not really the
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best way
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to do that right it gets kind of tedious
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at this point the output can be
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humongous
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the shell is not really the best place
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to read through such big output I mean e
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shell is
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probably one of the better shells for
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this because it's just a regular Emacs
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buffer but still
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it's not really the best tool and I need
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to repeat the command
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all the time until I finally build the
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right query
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and all the time I use I lose my
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focus I lose what I'm currently looking
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at
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I'm seeing the new result it would be so
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much nicer to have live feedback
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and when working with Emacs we're quite
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used to that so there should be an
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option
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and of course there is it's Emacs right
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so you can do anything
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there is various good tools for
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completion in Emacs
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I used ivy for this
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I'm going to code the usp for ivy
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iv is a generic completion mechanism for
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Emacs
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while it operates similarly to other
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completion schemes
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such as icomplete mode iv aims to be
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more efficient smaller
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simpler and smoother to use yet highly
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customizable
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and that's true one of the cool things
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of iv
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compared to other completion mechanisms
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in Emacs
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is that it can be used on dynamic
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data so usually completion works on a
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static input for example you're in a
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buffer a text buffer
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and you use I search maybe with idle
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mode
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and you find your results that's all
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nice
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however if I
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want to search on dynamic data that
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doesn't work
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so whenever I type in my query
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for jq I actually need to call the jq
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binary
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and it will give a different result set
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back so it's a really
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dynamic mechanism that we need here it's
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much more like a search engine
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and ivy luckily has something built in
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and it's called
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console so I used council and jq
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and combined them and build a new
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package
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with which we can use Emacs and jq
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to have live feedback
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it's very easy to use so you just call
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console.jq
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on a buffer containing json for example
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the one we have here
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let's call console.jq on it and we
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already
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get a default query the dot query which
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just gives us
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the same file but now we can change it
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and for example
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find all the keys in here and then we
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see I had this issue this was the one
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that we were interested in
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so let's find more information on the
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issue what
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keys does it have actually have uh it
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has assignees that that interests me
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so let's check out the assignees in here
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there's two of them but I'm only
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interested in the first one
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I'm making stuff up as I go here of
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course
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and whenever I hit enter I get a new
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buffer
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which just shows me this
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particular result for the particular
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query that I entered
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so let me do that again we are in here
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we are looking at a
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json file this can be very very big
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doesn't also need to be a file just
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needs to be a buffer
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you call console.jq on it and you can do
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any kind of
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query on it for example let's see if
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there is a url here
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yes there's a url let's see if there's a
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repository here repository
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no there isn't what was it called issue
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keys repository url it was called okay
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so let's see issue pause
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url and then we see so
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apparently this issue command is for a
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repository called
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organize I wonder what that might be
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okay so that was a very short
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introduction to console jq
0:08:52.640,0:08:56.800
you can see the timer here I only have
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one minute left to go so I'm going to
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leave
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with a very very short introduction to
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the console gq
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code it's not even 60 lines
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of e-lisp so building something like
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this is very very easy
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I would encourage you to go and read
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through the code in your own time
0:09:14.560,0:09:18.320
if you're interested in building
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something like this if you're interested
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in just using
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jq or you're done
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these are the links to all the tools
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console.jq of course
0:09:25.839,0:09:29.519
is readily available on melpah also
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developed
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under the agpl license on github
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and disorganized thing by the way it's
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orig mode for mobile and desktop
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browsers also a great
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free software tool maybe that interests
0:09:42.399,0:09:46.240
you
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thank you for listening have great time
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10 seconds left I am going to stop this
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now
0:09:49.360,0:09:53.920
enjoy EmacsConf have a great day
