[Haskell-beginners] Haskell package maturity

Wed Sep 30 13:44:04 UTC 2015

Andrew,

I understand why you're concerned, but I would encourage you to press
onward.  In my experience - building commercial web applications in Haskell
for the last 4 years - Haskell's library ecosystem works very well in
practice.

In a recent project, I was able to run an interesting experiment: half my
team (and half my code) was using JavaScript, and half was using Haskell.
In both cases, we made an effort to avoid "not invented here" syndrome, and
I think we largely succeeded in maintaining the right mentality about
outside libraries.  However, the *results* of that mentality were very
different in these two cases.  In the case of JavaScript, for any problem
we had, there were many libraries that tried to solve it.  That was
awesome.  However, before integrating a library, we had to spend a lot of
time testing it, making sure it wouldn't interfere with our existing code,
and integrating it.  After 2 years, we had about 10 JS library
dependencies, and we had gone through 10 or 20 more - integrated them,
found they had serious issues, and then been forced to replace them.

In Haskell, there were usually only one or two choices for a particular
problem.  However, with a cursory glance of the code, we were usually able
to determine that the code didn't do anything nasty.  With QuickCheck and
ghci, we were able to test things out very rapidly, to make sure they
basically worked.  Although cabal hell did occasionally rear its head, we
were very strict about dependency versioning (eventually adopting Nix,
which has very good Haskell support, to lock everything down) which meant
that only the person working on the library integration had to deal with
any sort of hell, and the rest of the team could simply pull and build.  By
the end of the project, we were using over 80 libraries from Hackage (more
than 200, if you count dependencies-of-dependencies), there was only one
time we had to replace a library that had made it past our initial vetting
process.

I don't know much about how Hackage works or what the download counts
represent, but I have found the download counts to be a useful, very rough
approximation of relative popularity.  If one library has wildly more
downloads than another, I'll often look at it first - although, I'll
usually look at the other ones as well, eventually.

Although the version numbers can look strange, you should know that the
Package Version Policy (PVP) counts both the first and second digit groups
as "Major version" numbers, with the first group usually used incremented
only when the project is seriously overhauled.  So, many projects stay at
0.1 indefinitely.  For example, the containers library
<https://hackage.haskell.org/package/containers> is currently at version
0.5.6.3, despite being very mature, completely stable, and in use by
thousands of projects.  About 10% of the 200 transitive dependencies in my
earlier project were version 0.1.something.

So, to make a long story short, my experience with Hackage libraries has
been overwhelmingly positive.  The success rate with integrations has been
over 98%, and the vetting and integration process has generally been quick
and painless.  Compared to the other ecosystems I've had experience with,
I've been able to integrate - and *keep* integrated, for the long haul -
far more code from Hackage than from anywhere else.

I hope you'll give it a shot, and I think you'll be pleasantly surprised by
how things turn out.

Regards,
Ryan

On Wed, Sep 30, 2015 at 6:22 AM, emacstheviking <objitsu at gmail.com> wrote:

> Andrew,
>
> The sheer number of packages is overwhelming and you can spend a very long
> time indeed trying to find something "suitable"... which... eventually may
> lead one to the conclusion, "It'll be quicker to roll my own" and then
> "Hey, I will upload it to Hackage, someone else might like it"... and so
> the list grows and grows and what began as an altruistic thought serves
> only to make it harder for the next guy to "find a suitable package".
>
> Personally, I've walked away from Haskell purely because I got fed up
> being continually bitten by "cabal hell".
> It's a shame because apart from LISP no other language has had such an
> impact on my thinking.
>
> I did find that whatever package I used though, they tend to work, so
> maybe take the first one and get on with it, that's what I used to do.
>
> Hope that helped, it probably didn't.
> All the best,
> Sean Charles.
>
>
> On 28 September 2015 at 16:15, Andrew Bernard <andrew.bernard at gmail.com>
> wrote:
>
>> Since starting to look on Hackage for packages for such vital things as
>> queues and algorithms, I am surprised to see very low numbers of downloads
>> for packages that seem to me to be vitally important. For example,
>> queuelike has only been downloaded 1617 times since being uploaded in 2009.
>> Similar very low numbers seem to apply for many packages. Another example
>> is cubicspline with only 485 downloads.
>>
>> My question is, are the numbers on Hackage correct, and if so, do they
>> indicate hardly anybody uses them, or indeed Haskell? I am starting to
>> wonder.
>>
>> I also notice version numbers are very low, often less than one and most
>> often around 0.1 or so. This is either a display of extreme modesty on the
>> part of Haskell library code developers (in fact, often found in open
>> source communities), or an indication of lack of maturity of the code.
>> Overall I am puzzled about this. I am trying to establish what packages to
>> use in my coding and there seems to be little indication of what to choose,
>> and how to assess code maturity. What am I missing?
>>
>> Andrew
>>
>>
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