Re: Guile equivalent to JS promises?

[swedebugia]

Hi

On 2018-12-10 15:37, Thompson, David wrote:
> Hello!
> 
> On Sun, Dec 9, 2018 at 5:52 AM <address@hidden> wrote:
>>
>> Hi
>>
>> I'm trying to understand JS promises.
>>
>> Are promises relevant in Guile?
>>
>> According to https://www.promisejs.org/ they seem to be a tool to
>> read/write JSON in a nonblocking way.
>>
>> Is this related to threading where the JS dev want multiple threads to
>> read stuff asynchroniusly at the same time?
> 
> So, promises are basically just callback functions + error handling +
> a way to compose them together in a chain.  I don't know of any
> existing Guile library that implements this API, but it wouldn't take
> much code to make a Scheme equivalent.  However, I am hesitant to
> recommend promises for writing asynchronous programs for a variety of
> reasons. [1]
> 
> Fortunately, Guile is pretty neat and provides a low-level feature
> that allows for much nicer asynchronous programming models: delimited
> continuations. I won't go into much detail about them here (see
> call-with-prompt in the manual), but Andy Wingo's guile-fibers [2]
> project is a really neat asynchronous programming library built on top
> of delimited continuations.
> 
> And here's my favorite guile-user post of all time in which Andy drops
> a 13 line coroutine implementation (this blew my mind many years ago):
> https://lists.gnu.org/archive/html/guile-user/2011-02/msg00031.html
> 
> tl;dr - use a system based on delimited continuations or write your own!
> 
> Hope this helps!
> 
> - Dave
> 
> [1]
> http://wingolog.org/archives/2016/10/12/an-incomplete-history-of-language-facilities-for-concurrency
> [2] https://github.com/wingo/fibers

Thanks for the insights. :)

Guile is indeed pretty neat. Thanks for the link. I started reading some
of wingos blog. Some of it still goes way over my head but i'm learning.

-- 
Cheers 
Swedebugia