From: Christopher Allan Webber Date: Sun, 25 Dec 2016 15:31:45 +0000 (-0600) Subject: doc: Add "A silly little IRC bot" section to new manual. X-Git-Tag: v0.4.0~50 X-Git-Url: https://jxself.org/git/?p=8sync.git;a=commitdiff_plain;h=b96db22e8626b8814649f584ce899dad6d9a070e doc: Add "A silly little IRC bot" section to new manual. * doc/8sync-new-manual.org: Add "A silly little IRC bot" section. --- diff --git a/doc/8sync-new-manual.org b/doc/8sync-new-manual.org index 0115003..e2bb333 100644 --- a/doc/8sync-new-manual.org +++ b/doc/8sync-new-manual.org @@ -111,11 +111,300 @@ how easy it is to add new networked layers by tacking on a high score to our game, and as a finale we'll dive into writing our own little irc bot framework "from scratch" on top of the 8sync actor model. -Alright, let's get going. +Alright, let's get started. This should be a lot of fun! ** A silly little IRC bot +First of all, we're going to need to import some modules. Put this at +the top of your file: + +#+BEGIN_SRC scheme + (use-modules (8sync) ; 8sync's agenda and actors + (8sync systems irc) ; the irc bot subsystem + (oop goops) ; 8sync's actors use GOOPS + (ice-9 format) ; basic string formatting + (ice-9 match)) ; pattern matching +#+END_SRC + +Now we need to add our bot. Initially, it won't do much. + +#+BEGIN_SRC scheme + (define-class ()) + + (define-method (handle-line (irc-bot ) speaker channel + line emote?) + (if emote? + (format #t "~a emoted ~s in channel ~a\n" + speaker line channel) + (format #t "~a said ~s in channel ~a\n" + speaker line channel))) +#+END_SRC + +We've just defined our own IRC bot! +This is an 8sync actor. +(8sync uses GOOPS to define actors.) +We extended the handle-line generic method, so this is the code that +will be called whenever the IRC bot "hears" anything. +For now the code is pretty basic: it just outputs whatever it "hears" +from a user in a channel to the current output port. +Pretty boring! +But it should help us make sure we have things working when we kick +things off. + +Speaking of, even though we've defined our actor, it's not running +yet. Time to fix that! + +#+BEGIN_SRC scheme +(define* (run-bot #:key (username "examplebot") + (server "irc.freenode.net") + (channels '("##botchat"))) + (define hive (make-hive)) + (define irc-bot + (hive-create-actor* hive "irc-bot" + #:username username + #:server server + #:channels channels)) + (run-hive hive (list (bootstrap-message hive irc-bot 'init)))) +#+END_SRC + +Actors are connected to something called a "hive", which is a +special kind of actor that runs all the other actors. +Actors can spawn other actors, but before we start the hive we use +this special "hive-create-actor*" method. +It takes the hive as its first argument, the actor class as the second +argument, a decoraive "cookie" as the third argument (this is +optional, but it helps with debugging... you can skip it by setting it +to #f if you prefer), and the rest are initialization arguments to the +actor. hive-create-actor* passes back not the actor itself (we don't +get access to that usually) but the *id* of the actor. +(More on this later.) +Finally we run the hive with run-hive and pass it a list of +"bootstrapped" messages. +Normally actors send messages to each other (and sometimes themselves), +but we need to send a message or messages to start things or else +nothing is going to happen. + +We can run it like: + +#+BEGIN_SRC scheme +(run-bot #:username "some-bot-username") ; be creative! +#+END_SRC + +Assuming all the tubes on the internet are properly connected, you +should be able to join the "##botchat" channel on irc.freenode.net and +see your bot join as well. +Now, as you probably guessed, you can't really /do/ much yet. +If you talk to the bot, it'll send messages to the terminal informing +you as such, but it's hardly a chat bot if it's not chatting yet. + +So let's do the most boring (and annoying) thing possible. +Let's get it to echo whatever we say back to us. +Change handle-line to this: + +#+BEGIN_SRC scheme + (define-method (handle-line (irc-bot ) speaker channel + line emote?) + (<- irc-bot (actor-id irc-bot) 'send-line channel + (format #f "Bawwwwk! ~a says: ~a" speaker line))) +#+END_SRC + +This will do exactly what it looks like: repeat back whatever anyone +says like an obnoxious parrot. +Give it a try, but don't keep it running for too long... this +bot is so annoying it's likely to get banned from whatever channel +you put it in. + +This method handler does have the advantage of being simple though. +It introduces a new concept simply... sending a message! +Whenever you see "<-", you can think of that as saying "send this +message". +The arguments to "<-" are as follows: the actor sending the message, +the id of the actor the message is being sent to, the "action" we +want to invoke (a symbol), and the rest are arguments to the +"action handler" which is in this case send-line (with itself takes +two arguments: the channel our bot should send a message to, and +the line we want it to spit out to the channel). + +(Footnote: 8sync's name for sending a message, "<-", comes from older, +early lisp object oriented systems which were, as it turned out, +inspired by the actor model! +Eventually message passing was dropped in favor of something called +"generic functions" or "generic methods" +(you may observe we made use of such a thing in extending +handle-line). +Many lispers believe that there is no need for message passing +with generic methods and some advanced functional techniques, +but in a concurrent environment message passing becomes useful +again, especially when the communicating objects / actors are not +in the same address space.) + +Normally in the actor model, we don't have direct references to +an actor, only an identifier. +This is for two reasons: to quasi-enforce the "shared nothing" +environment (actors absolutely control their own resources, and +"all you can do is send a message" to request that they modify +them) and because... well, you don't even know where that actor is! +Actors can be anything, and anywhere. +It's possible in 8sync to have an actor on a remote hive, which means +the actor could be on a remote process or even remote machine, and +in most cases message passing will look exactly the same. +(There are some exceptions; it's possible for two actors on the same +hive to "hand off" some special types of data that can't be serialized +across processes or the network, eg a socket or a closure, perhaps even +one with mutable state. +This must be done with care, and the actors should be careful both +to ensure that they are both local and that the actor handing things +off no longer accesses that value to preserve the actor model. +But this is an advanced topic, and we are getting ahead of ourselves.) +We have to supply the id of the receiving actor, and usually we'd have +only the identifier. +But since in this case, since the actor we're sending this to is +ourselves, we have to pass in our identifier, since the Hive won't +deliver to anything other than an address. + +Astute readers may observe, since this is a case where we are just +referencing our own object, couldn't we just call "sending a line" +as a method of our own object without all the message passing? +Indeed, we do have such a method, so we /could/ rewrite handle-line +like so: + +#+BEGIN_SRC scheme + (define-method (handle-line (irc-bot ) speaker channel + line emote?) + (irc-bot-send-line irc-bot channel + (format #f "Bawwwwk! ~a says: ~a" speaker line))) +#+END_SRC + +... but we want to get you comfortable and familiar with message +passing, and we'll be making use of this same message passing shortly +so that /other/ actors may participate in communicating with IRC +through our IRC bot. + +Anyway, our current message handler is simply too annoying. +What would be much more interesting is if we could recognize +when an actor could repeat messages /only/ when someone is speaking +to it directly. +Luckily this is an easy adjustment to make. + +#+BEGIN_SRC scheme + (define-method (handle-line (irc-bot ) speaker channel + line emote?) + (define my-name (irc-bot-username irc-bot)) + (define (looks-like-me? str) + (or (equal? str my-name) + (equal? str (string-concatenate (list my-name ":"))))) + (when (looks-like-me?) + (<- irc-bot (actor-id irc-bot) 'send-line channel + (format #f "Bawwwwk! ~a says: ~a" speaker line)))) +#+END_SRC + +This is relatively straightforward, but it isn't very interesting. +What we would really like to do is have our bot respond to individual +"commands" like this: + +#+BEGIN_SRC text + examplebot: hi! + Oh hi foo-user! + examplebot: botsnack + Yippie! *does a dance!* + examplebot: echo I'm a very silly bot + I'm a very silly bot +#+END_SRC + +Whee, that looks like fun! +To implement it, we're going to pull out Guile's pattern matcher. + +#+BEGIN_SRC scheme + (define-method (handle-line (irc-bot ) speaker channel + line emote?) + (define my-name (irc-bot-username irc-bot)) + (define (looks-like-me? str) + (or (equal? str my-name) + (equal? str (string-concatenate (list my-name ":"))))) + (match (string-split line #\space) + (((? looks-like-me? _) action action-args ...) + (match action + ;; The classic botsnack! + ("botsnack" + (<- irc-bot (actor-id irc-bot) 'send-line channel + "Yippie! *does a dance!*")) + ;; Return greeting + ((or "hello" "hello!" "hello." "greetings" "greetings." "greetings!" + "hei" "hei." "hei!" "hi" "hi!") + (<- irc-bot (actor-id irc-bot) 'send-line channel + (format #f "Oh hi ~a!" speaker))) + ("echo" + (<- irc-bot (actor-id irc-bot) 'send-line channel + (string-join action-args " "))) + + ;; ---> Add yours here <--- + + ;; Default + (_ + (<- irc-bot (actor-id irc-bot) 'send-line channel + "*stupid puppy look*")))) + ;; Otherwise... just spit the output to current-output-port or whatever + (_ + (if emote? + (format #t "~a emoted ~s in channel ~a\n" + speaker line channel) + (format #t "~a said ~s in channel ~a\n" + speaker line channel))))) +#+END_SRC + +Parsing the pattern matcher syntax is left as an exercise for the +reader. + +If you're getting the sense that we could make this a bit less wordy, +you're right: + +#+BEGIN_SRC scheme + (define-method (handle-line (irc-bot ) speaker channel + line emote?) + (define my-name (irc-bot-username irc-bot)) + (define (looks-like-me? str) + (or (equal? str my-name) + (equal? str (string-concatenate (list my-name ":"))))) + (define (respond respond-line) + (<- irc-bot (actor-id irc-bot) 'send-line channel + respond-line)) + (match (string-split line #\space) + (((? looks-like-me? _) action action-args ...) + (match action + ;; The classic botsnack! + ("botsnack" + (respond "Yippie! *does a dance!*")) + ;; Return greeting + ((or "hello" "hello!" "hello." "greetings" "greetings." "greetings!" + "hei" "hei." "hei!" "hi" "hi." "hi!") + (respond (format #f "Oh hi ~a!" speaker))) + ("echo" + (respond (string-join action-args " "))) + + ;; ---> Add yours here <--- + + ;; Default + (_ + (respond "*stupid puppy look*")))) + ;; Otherwise... just spit the output to current-output-port or whatever + (_ + (if emote? + (format #t "~a emoted ~s in channel ~a\n" + speaker line channel) + (format #t "~a said ~s in channel ~a\n" + speaker line channel))))) +#+END_SRC + +Okay, that looks pretty good! +Now we have enough information to build an IRC bot that can do a lot +of things. +Take some time to experiment with extending the bot a bit before +moving on to the next section! +What cool commands can you add? + +** An intermission: about live hacking + ** Battle bot! ** Adding a "rankings" web page