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Yetibot workshop

Agenda

  • Yetibot usage fundamentals
  • Livecode a Yetibot feature with the REPL
  • Clojure language basics
  • Resources for getting started
  • Open time for questions, play, hacking on Yetibot

Yetibot usage fundamentals

Instead of working through Yetibot's primitives and its many individual capabilities we'll start with a non trivial expression that's made up of several levels of nested aliases composed of piped commands. This will better illustrate how such primitives can be combined into something useful fun.

!repeat 5 yetishould

To start unpacking this we can use help:

!help yetishould

Help shows us that it's an alias for an expression:

TODO - allow multiline yetibot expressions

list batman insanity kahn gasp
  | random
  | meme %s: yetibot
    `list should, should not, must, must not | random`
    `randshould`

Out of the commands in that expression we can see:

  1. list used to build up a list of memes
  2. random to select a random meme from the list
  3. meme to generate a meme
  4. sub expression to randomly choose from "should", "should not", "must" and "must not
  5. randshould, which is itself an alias.

Let's unpack randshould:

!help randshould
randshould # alias for randletter | complete should i | random | sed s/should i/ | trim

Unpack its contents:

!help randletter
randletter # alias for range 65 91 | xargs echo | random | js String.fromCharCode(%s)

Finally we have expanded all the way down to built in commands. Let's take a look at each one:

!help range
range <end> # create a list from 0 to <end> (exclusive)
range <start> <end> # create a list from <start> (inclusive) to <end> (exclusive)
range <start> <end> <step> # create a list from <start> (inclusive) to <end> (exclusive) by <step>

Examples:
range 2 => 0 1
range 2 4 => 2 3
range 0 6 2 => 0 2 4

Results are returned as collections.

!help xargs
xargs <cmd> <list> # run <cmd> for every item in <list> in parallel; behavior is
similar to xargs(1)'s xargs -n1

!help random
random <list> # returns a random item from <list>
random # generate a random number

!help sed

sed s/<search-pattern>/<replace-pattern> <string> # replace <search-pattern>
with <replace-pattern> on piped contents

sed s/<search-pattern/ <string> # replace <search-pattern> with nothing on piped
contents

Values

At its most basic level, Yetibot takes a command and outputs a response.

!echo ebay

Pipes

Pipes let us compose the output from multiple commands in a series to a single response:

!echo ebay | echo are | echo we

Subexpressions

We can also embed commands with sub expressions:

!echo we $(echo are $(echo ebay))

Collections

A Yetibot response can be a collection of values instead of a single value. Yetibot will output each item in the collection on its own line.

The list command builds a collection using space or comma-separated items:

!list one two three
!list this is, also a collection

Custom rendering of data

One of the more interesting recent concepts in Yetibot is data behind pipes.

Data and render

Aliases

As we've seen, Yetibot commands can be quite expressive, but as they grow in complexity they become harder to invoke. This is where aliases come in.