[Haskell-cafe] who's in charge?

Günther Schmidt gue.schmidt at web.de
Thu Oct 28 20:30:09 EDT 2010

Dear John,

Am 29.10.10 01:23, schrieb John Goerzen:
> On 10/28/2010 05:44 PM, Günther Schmidt wrote:
>>> There is no need for a mail client library on many platforms. Just
>>> pipe the data to /usr/sbin/sendmail and poof. Done.
>> That would work well for sending (on Unix), but not for receiving.
> Quite true.  For receiving, we have tools like fetchmail, imapsync, 
> offlineimap, MH, the list goes on.
> The Unix philosophy is all about pluggable bits and pieces that can be 
> reused all over the place.  I like that philosophy.  It means that one 
> doesn't have to reinvent mail handling n times for n languages.  As 
> long as your language can do some piping, you can handle the basics of 
> mail.
> Now, I'll grant you that fetchmail won't solve every possible mail 
> access scenario.  It isn't, for instance, good enough to be the 
> backend of OfflineIMAP.  But I do want to push back on the notion 
> that, on POSIX platforms, these things have to be reinvented for each 
> language.  It just isn't so.
>>> Has it occurred to you that there is no mail client library because
>>> there is no need for one?
>> No, to be honest, it never has. I absolutely cannot conceive of it. It'd
>> be like not having HDBC for instance and having to roll my own database
>> driver. It wouldn't have mattered how great a language haskell is, had
> Hmm, I am perhaps uniquely qualified to say "been there, done that" ;-)
> The existing Haskell database drivers at the time didn't meet my 
> needs.  They lacked some things I considered rudimentary and 
> standard.  I felt about them approximately the way you did about mail.
> I decided that Haskell would be enough of a long-term win to justify 
> writing HDBC.  So I did, and I'm glad of it.
> I think you are getting some resistance here because you appear to be 
> demanding that others volunteer their time to meet your pet need.

Well this is exactly what I have the most problem with. This assumption. 
It is exactly this where I am seriously taking offense. I suddenly am 
taking fire from all sides for things that were actually said more 
bluntly by people before me. One of the responses out of the hysteria 
that developed even suggested I was calling for a dictator. Get a grip.

Other people before me lamented about the lack of a good email client 
library as can be seen here:


Do not assume that the words that were put into my mouth by hysterical 
posters are indeed my own, they are not. Consider what I did say and not 
what others suggest I did.

I also noticed that one of your co-authors made statements regarding the 
quality of available libraries on hackage, without being blown to bits. 
My own posts in this thread did not come close to even suggesting that.

> This attitude doesn't usually work.
Nor should it.
>> it not had HDBC I would have had no choice but to drop it and move on.
> Or you could have written HDBC.  Or you could have used unixODBC, 
> which already solved that problem.  (Whoops, did I do a tiny bit of 
> wheel reinvention myself?  Indeed I did, with the PostgreSQL HDBC 
> backend. There are reasons for it though.)
>> Database connectivity to me is one of the essential things I need to be
>> able to do, and so is email, as is xml, as is http.
> HTTP is another thing that can easily be "outsourced".  I've been 
> somewhat unhappy at various points in time with the Haskell HTTP 
> libraries.  No problem, though; there's always Curl.  One can choose 
> the Haskell libcurl binding or call the Curl binary directly; it's 
> even portable to all sorts of platforms, and you get not just HTTP, 
> but FTP, Gopher, SCP, and some other useful protocols along for the ride.
>> Well it's not necessarily only about sending mail, it's more about the
>> whole shebang one wants / needs to do with mail.
> So if it's not about sending, it's about receiving or accessing stored 
> mail.
> The Maildir spec is very simple and easily implemented.  Google tells 
> me there is an implementation in xmonad already.  Tools to get mail 
> into Maildirs are plentiful and featureful.

I appreciate that you are a proficient Unix / Posixler but it just so 
happens that I was thinking more about accessing POP3 account, which I 
imagine to a fairly common usage scenario. To my defense I did mention 
that the lack of certain libraries does not cause the same problem to 
more capable people, such as yourself, as they do to people less 
capable. Hey you rolled your own database access library (and shared it, 
much appreciated). But most would struggle with such a lack.

There is this one posters who likes to repeatedly point out how none of 
his programs ever needed email, so how could it be a problem then. Well 
good for him, but in my experience it's needed.

> My point is this: using existing tools on your system, and turning a 
> blind eye to their implementation language, can be a perfectly 
> workable, and even elegant, solution.
> Example: say you needed to copy a directory containing files and 
> directories.  Is that easy to do?  You could probably whip up some 
> sort of recursive file copying thing to do that in a few lines of 
> code.  But will it handle things like preserving permissions bits, 
> ownership, ACLs, symbolic links, not following symlinks, etc. 
> correctly?  We already have a tool that does all those things (cp -a), 
> so using it is, in my book, more elegant than writing a (probably more 
> buggy and certainly less tested) clone.
> So I'm pushing back on your unstated premise; namely, that a Haskell 
> library for mail handling is necessary for efficient mail handling in 
> Haskell.  I don't think it is.

duly noted :)

> -- John

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