[Haskell-cafe] Help to choose a library name

Wed Jun 29 08:31:53 UTC 2016

I understand, my comment was just on the syntax.
Actually I have the same problem with "guard":

test x = do
   guard x
   XXXXXXXXX
   YYYYYYYYY
   ....

Unless I read all the monad body, there is no visual cue that XXX and YYY
might not be run.
The control flow is not syntactically visible.
That's why I prefer using guards like that:

test x = do
   guard x >> do
      XXXXXXXXX
      YYYYYYYYY
      ....

Here the indentation shows that there is a control flow decision.
Is it possible to do the same thing with Transient?
Something like:

main = keep $ do
    async (return "hello") <|> async (return "world") >>= \r -> do
       liftIO $ print r

On Tue, Jun 28, 2016 at 7:25 AM, Geraldus <heraldhoi at gmail.com> wrote:

> This is because the whole computation is kept (via `keep`).  If you just
> run computation with `runTransient` you will see only “world” in output and
> then program ends, however since the computation is kept when second action
> finishes it prints “hello”.
>
> `r <- async … <|> async …`
> Here `r` is a continuation, everything below it will be re-computed when
> any of alternatives will return a result.  For example, you can add another
> choice:
> `r <- async … <|> async … <|> waitEvents someEventAction`
> In this case every time your `someEventAction` returns a value `r` takes
> it and the rest of code re-executed (or in other words when you have a new
> continuation the computation re-evaluated).
>
> Hope this makes sense.
>
> вт, 28 июн. 2016 г. в 3:31, Corentin Dupont <corentin.dupont at gmail.com>:
>
>> Wow, it is very impressive. I need to give it more time.
>> I have one question regarding this example:
>>
>> main = keep $ do
>>     th <- liftIO myThreadId                                   -- thread 89
>>     r <- async (do threadDelay 1000000; return "hello")       -- thread 90
>>          <|> async (return "world")                           -- thread 91
>>     th' <- liftIO myThreadId                                  -- thread 90 and 91
>>     liftIO $ print (th, th', r)                               -- thread 90 and 91
>>
>> Output:
>>
>> (ThreadId 89,ThreadId 91,"world")
>> (ThreadId 89,ThreadId 90,"hello")
>>
>>
>> For me it's counter-intuitive that there are two outputs. What is the
>> reason behind?
>> It seems that the use of the <|> affects the rest of the program.
>> It looks strange to me because the two lines situated after the <|> does
>> not look "syntactically" involved, if you see what I mean.
>> Instead I was expecting only one output, with the first thread to finish
>> "wins".
>> In fact I implemented it like that:
>> http://www.corentindupont.info/blog/posts/Programming/2014-09-23-Nomyx-Language.html#event-alternative-interface
>>
>> Cheers
>> Corentin
>>
>>
>> On Mon, Jun 27, 2016 at 8:22 PM, Geraldus <heraldhoi at gmail.com> wrote:
>>
>>> Sorry, here is some links:
>>> Wiki paga on GitHub
>>> https://github.com/agocorona/transient/wiki/Transient-tutorial
>>> Programming at specification level
>>> https://github.com/agocorona/transient/wiki/Programming-at-the-specification-level
>>>
>>> пн, 27 июн. 2016 г. в 23:19, Geraldus <heraldhoi at gmail.com>:
>>>
>>>> Hi!  Have you looked at Transient by Alberto Gomez Corona?
>>>>
>>>> пн, 27 июн. 2016 г. в 18:27, Corentin Dupont <corentin.dupont at gmail.com
>>>> >:
>>>>
>>>>> Hi Joachim,
>>>>> I agree... I looked hard at them :)
>>>>> https://wiki.haskell.org/Functional_Reactive_Programming
>>>>>
>>>>> I need a library with a DSL able to create forms on the fly, in a
>>>>> "demand driven" way.
>>>>> I.e. if at some point in time the user program needs a boolean from
>>>>> the user, a radio button will be created on the screen of that user. The
>>>>> objective is to retrieve the boolean, creating the form is just a way to do
>>>>> that. Complex forms can be created, capable of generating full ADTs. The
>>>>> styling of the form is not important.
>>>>> Other requirements:
>>>>> - it should be possible to run the event DSL in a monad different from
>>>>> IO.
>>>>> - the event DSL need to be instance of Alternative: events can be put
>>>>> in concurrence, the first to fire wins.
>>>>>
>>>>>
>>>>>
>>>>>
>>>>> On Mon, Jun 27, 2016 at 10:25 AM, Joachim Breitner <
>>>>> mail at joachim-breitner.de> wrote:
>>>>>
>>>>>> Hi,
>>>>>>
>>>>>> Am Montag, den 27.06.2016, 09:38 +0200 schrieb Corentin Dupont:
>>>>>> > I need it for the game Nomyx, but couldn't find the features I
>>>>>> wanted
>>>>>> > from the existing libraries.
>>>>>>
>>>>>> any chance to extend existing libraries to support what you need?
>>>>>> Library proliferation does not really help the ecosystem.
>>>>>>
>>>>>> Greetings,
>>>>>> Joachim
>>>>>> --
>>>>>>
>>>>>> Joachim “nomeata” Breitner
>>>>>>   mail at joachim-breitner.de • https://www.joachim-breitner.de/
>>>>>>   XMPP: nomeata at joachim-breitner.de • OpenPGP-Key: 0xF0FBF51F
>>>>>>   Debian Developer: nomeata at debian.org
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>>>>>
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>>>>
>>
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