[Haskell-cafe] Re: Ubuntu and ghc

[Claus Reinke]

>> Well, that's true.  I guess what I'm really objecting to in Claus's message 
>> is the implication that we should always use a Haskell Installation 
>> Manager, even on systems with good built-in package management.

what was implied was that haskell installation manager (HIM) 
and native package managers (NPM) (where they exist) should 
collaborate, so that NPMs know how to extract dependencies 
from haskell packages, and HIM knows how to extract 
dependencies (haskell or otherwise) from NPMs.

for the NPM-calls-HIM direction, that could be dynamically
or, as in current practice, in a separate phase converting HIM
to NPM packages.

for the HIM-calls-NPM direction, that would simply present
a haskell view on the native software (ie, cabal install/list/..
negotiating with NPM). whereas, currently, if i understand
correctly, systems with NPM will have many haskell packages
under NPM control and some haskell packages under HIM
control and some haskell packages under no control whatsoever
(eg, installing tools or compilers leaves no record, necessitating
use of autoconf & co).

i'm not saying "reimplement and ignore NPMs", i'm saying
"NPMs and HIM should collaborate". if anything, that would
reduce the number of exceptions where haskell packages are 
installed without the NPM knowing about them. and i'd like
to see fewer cases where HIM forgets about what it or NPM have installed.

so, on systems with NPM, users have a choice of interface, 
but nothing bad will happen no matter whether they choose 
NPM directly or HIM as an interface to it. and haskell
book and tutorial authors only need to explain HIM, and
its commands will just work - independent of the variant 
or lack of NPM on the reader's system.
 
is that still objectionable?-)
claus

ps. it is a lot like using fmap, no matter what the Functor
    is, or using something like System.Process, no matter
    whether or not the OS supports that easily.

>> Yes, I agree we need good support for managing packages for the other 
>> scenarios: no system package manager, home-directory installs, no 
>> pre-prepared system package.  I just don't want whatever provision we make 
>> for these cases to replace the system package manager for global package 
>> installs on systems where that is well supported.
> 
> Indeed. I wholly agree.
> 
> Duncan
> 
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