[Haskell-cafe] Minimal Haskell Platform
rendel at informatik.uni-marburg.de
Tue Apr 15 07:09:59 UTC 2014
Simon Hengel wrote:
> Where would something like the HP actually make sense?
In my experience, the Haskell Platform makes it significantly easier to
use Haskell on Windows.
On Windows and/or for the typical Haskellers on Windows, it is hard to
build a package that depends on external C libraries or uses a configure
script, however trivial. This is because on Windows, there is no way to
manage installed C libraries without understanding C development. But
most Windows users are not C programmers, and some Windows Haskellers
even learn Haskell as their first programming language. In extreme
cases, ghc and cabal are the first command-line tool they learn.
So on Windows, before the Haskell Platform was introduced, `cabal
install some-random-package` usually failed for some dependency that
required a C library. With the Haskell Platform, `cabal install
some-random-package` usually works. I guess there are two effects:
1. The Haskell platform seems to bundle some packages that require
external C libraries or configure scripts. The network package comes to
2. The existence of the Haskell platform encourages non-Windows
developers to avoid dependencies that are not in the Haskell platform.
Because of effect 1, this translates to non-Windows developers avoiding
dependencies that are hard to install on Windows.
So from the perspective of using Haskell on Windows, the Haskell
Platform is very successful, and installing it is good advice. If
anything, it should be bigger, not smaller. And it should focus on
libraries with external dependencies.
So could we make a Haskell-on-Windows-Platform and drop the Haskell
Platform for the other platforms? This would give Haskellers on Windows
the first effect, but it would disable the second effect. I'm not sure
how much the first effect is worth without the second.
Why should we care about Haskellers on Windows? I think there are some
important classes of new Haskellers that are on Windows, at least
initially, and if we want to convert them to long-time Haskellers, we
need to support them in their context. For example, here are three
reasons to start your Haskell experience on Windows:
1. You might be a student at a university where the lab computers run
Windows. A minimal installation without excellent support for libraries
would be fine for following a lecture on Haskell, but you will not take
Haskell serious if it doesn't give you easy access to libraries. In
fact, installing Haskell libraries can be very easy, but only if you get
the external dependency issue out of the way.
2. You might be a not-yet-programmer who wants to use a embedded DSL
for your domain, and you're on Windows "by default" or because of the
tradition in your field. We like to claim that Haskell is good for
embedded DSLs, so we should support this usage scenario.
3. You might be a not-yet-programmer who wants to use an external DSL
for your domain, and you're on Windows as above, and you want to become
a power-user of the DSL. So maybe you start reporting bugs and are asked
to `cabal install` the development version to check fixes. Or maybe you
want to copy-and-adapt a little Haskell program that uses a library
interface to the DSL for scripting purposes. We see both of this
happening for pandoc, for example.
Also, Haskell is a high-level language, and it would be somewhat silly
if Haskell programs would not be easily portable due to low-level issues.
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