Hi Atamert - thanks :) I thought it might be preferable to keep the call to (latch)explicit - it means that ylet can be used in nested calls, too - for example, to set up and compose groups of components/sub-systems: (contrived example, though!)
;; (docs for ylet at https://github.com/james-henderson/yoyo#introducing-ylet ) (require '[yoyo :refer [ylet]]) (defn with-connections [config f] (ylet [db-pool (with-db-pool (:db config)) es-conn (with-es-connection (:elasticsearch config))] (f {:db-pool db-pool :es-conn es-conn}))) (defn make-system [latch] (let [config ...] (ylet [connections (with-connections system) _ (with-webserver {:handler (make-handler (merge connections {:config config})) :port 3000})] (latch)))) How would you see the with-* functions working, btw? Cheers, James On Tuesday, 23 June 2015 09:57:16 UTC+1, Atamert Ölçgen wrote: > > Hi James, > > Interesting idea. Thanks for sharing. > > I think you can simplify this: > > (yoyo/run-system! > (fn [latch] > (ylet [db-pool (with-db-pool {...}) > :let [server-opts {:handler (make-handler {:db-pool db-pool}) > :port 3000}] > web-server (with-web-server server-opts)] > (do-this web-server) > (do-that db-pool web-server) > (latch)))) > > > to: > > (yoyo/foo! [db-pool (with-db-pool {...}) > :let [server-opts {:handler (make-handler {:db-pool db-pool}) > :port 3000}] > web-server (with-web-server server-opts)] > (do-this web-server) > (do-that db-pool web-server)) > > > I believe with-* function can also be simplified further. > > > On Tue, Jun 23, 2015 at 1:18 AM, James Henderson <ja...@jarohen.me.uk > <javascript:>> wrote: > >> Hi all, >> >> I've just released an early version of 'Yo-yo', a protocol-less, function >> composition-based alternative to Component. It's still in its early stages, >> so feedback would be very much appreciated! >> >> https://github.com/james-henderson/yoyo >> >> Yo-yo was also an experiment to see what could be de-coupled from the >> concept of 'reloadable systems', so you won't find any configuration, >> dependency injection, etc - just a way to write a system that can be easily >> started, stopped, and reloaded. >> >> Fundamentally, we start by assuming there's a function available that >> only returns 'when the system stops' - a 'latch', say. If we had such a >> function, we could start our system, call that function, then stop the >> system (closing any necessary resources). A database pool, for example, >> might look like this: >> >> (defn with-db-pool [db-config f] >> (let [db-pool (start-pool! db-config)] >> (try >> (f db-pool) >> >> (finally >> (stop-pool! db-pool))))) >> >> Here, we're assuming that we'll be passed 'f', the 'latch' function. A >> web server would be similar, and, because they're both functions, they're >> very simple to compose: >> >> (with-db-pool {...} >> (fn [db-pool] >> (with-web-server {:handler (make-handler {:db-pool db-pool}) >> :port ...} >> (fn [web-server] >> ;; TODO: Ah. We've run out of turtles. :( >> )))) >> >> This is where Yo-yo comes in - there’s a function called run-system!, >> which takes a function that accepts a latch: >> >> (:require [yoyo]) >> >> (yoyo/run-system! >> (fn [latch] >> (with-db-pool {...} >> (fn [db-pool] >> (with-web-server {:handler (make-handler {:db-pool db-pool}) ; n.b. >> we have access to the db-pool here - no need for global state! >> :port ...} >> (fn [web-server] >> (latch))))))) ; Aha! >> >> run-system! then returns a promise - deliver any value to it, and it'll >> stop the system. >> >> And that's pretty much it! There are a few more functions - mostly to do >> with easily starting/stopping/reloading a system through the REPL, and a >> macro to simplify the 'function staircase' - these are covered in more >> detail in the README. There are some also common components - a database >> pool, a web server, and a simple integration for existing Component systems. >> >> It'd be great to hear your thoughts/ideas, whatever they may be - either >> through here, e-mail, Github, or Twitter - thanks! >> >> James >> >> -- >> You received this message because you are subscribed to the Google >> Groups "Clojure" group. >> To post to this group, send email to clo...@googlegroups.com >> <javascript:> >> Note that posts from new members are moderated - please be patient with >> your first post. >> To unsubscribe from this group, send email to >> clojure+u...@googlegroups.com <javascript:> >> For more options, visit this group at >> http://groups.google.com/group/clojure?hl=en >> --- >> You received this message because you are subscribed to the Google Groups >> "Clojure" group. >> To unsubscribe from this group and stop receiving emails from it, send an >> email to clojure+u...@googlegroups.com <javascript:>. >> For more options, visit https://groups.google.com/d/optout. >> > > > > -- > Kind Regards, > Atamert Ölçgen > > ◻◼◻ > ◻◻◼ > ◼◼◼ > > www.muhuk.com > -- You received this message because you are subscribed to the Google Groups "Clojure" group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en --- You received this message because you are subscribed to the Google Groups "Clojure" group. To unsubscribe from this group and stop receiving emails from it, send an email to clojure+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
