On Wednesday, 24 June 2015 11:17:41 UTC+1, Atamert Ölçgen wrote:
>
>
>
> On Tue, Jun 23, 2015 at 11:47 PM, James Henderson <[email protected]
> <javascript:>> wrote:
>
>> 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?
>>
>
> I think the general idea should be to provide a clean API to the consumer
> (of your lib). Perhaps something that accepts a start function, a stop
> function and some sort of main loop (f in your example).
>
Not sure I understand what you mean here? Tbh, I was trying to get away
from the idea of separate start & stop functions - it seems 'cleaner' to me
without them! (although of course that's subjective).
Also, the 'with-*' functions here are consumer code - the only Yo-yo
functions/macros in this example are 'run-system!' and 'ylet'. Yo-yo itself
is *tiny* (<100 LoC) - my aim was for a library that solely dealt with
starting/stopping a provided system, and *no more* :)
Maybe it'd be worth fleshing out an example of what you were looking for?
Cheers,
James
>
>>
>> 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 <[email protected]>
>>> 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
>>>>
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>>>
>>>
>>>
>>> --
>>> Kind Regards,
>>> Atamert Ölçgen
>>>
>>> ◻◼◻
>>> ◻◻◼
>>> ◼◼◼
>>>
>>> www.muhuk.com
>>>
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>
>
>
> --
> Kind Regards,
> Atamert Ölçgen
>
> ◻◼◻
> ◻◻◼
> ◼◼◼
>
> www.muhuk.com
>
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