Lurker speaks: I too came to the same conclusion as Michael a long time
back; I absolutely love Haskell but sooner or later it seemed to me that
the "dependancy hell" would kick in just when you least needed / expected
it to. It is the single biggest put off for me now to consider using it.
I too find myself back in Erlang and Prolog these days, and I have begun
learning OCaml instead as it offers a lot of things that Haskell seems but
without the pure functional venus flytraps of monads, state transformers
etc etc.
Not all jobbing developers are math majors or CS majors, some of us are
just mere mortals wishing to use shinier tools for a safer and more
rigorous path to freedom from day job hell!
But, SPJ et al.... f* awesome language!
:)
Sean
On 18 October 2014 13:16, Michael Martin
On 10/18/2014 02:31 AM, Heinrich Apfelmus wrote:
Michael L Martin wrote:
On 10/16/2014 03:11 PM, Mateusz Kowalczyk wrote:
Merely going from the error message and your steps, it seems to me that you're *not* meant to install GHC yourself first and that the platform ships with GHC. I would say try again but without installing GHC and cabal first.
Well, that didn't work, either:
mmartin@cloud:~/Downloads/haskell-platform-2014.2.0.0$ ./platform.sh .../ghc-7.8.3-x86_64-unknown-linux-deb7.tar.bz2 ../platform.sh: 18: ./platform.sh: cabal: not found *** *** Building hptool *** ../platform.sh: 29: ./platform.sh: cabal: not found mmartin@cloud:~/Downloads/haskell-platform-2014.2.0.0$
Apparently, different distributions of the Haskell Platform differ in what tools they package: the binary distribution includes GHC and cabal, whereas the source distribution, which you are currently trying to install, doesn't include GHC and cabal.
Judging from the error message
Stderr: mtl-2.1.3.1: package(s) with this id already exist: mtl-2.1.3.1
it seems that the platform tries to build the `mtl` package, but fails because it is already installed. You can use the command
$ ghc-pkg list
to see which packages are installed globally and in your home directory. Most likely, `mtl` got installed because you installed `cabal-install`. I have no idea how to deal with the conflict, though, I'm not really familiar with the Haskell platform source distribution.
Best regards, Heinrich Apfelmus
-- http://apfelmus.nfshost.com
Thanks, Heinrich.
I find it astonishing that build/install fails because it finds that a dependency that it needs is already installed. This is totally unreasonable. I was really looking forward to experimenting with Cloud Haskell, but the pain of installation, coupled with Haskell's well-known issues with "dependency hell", have soured me on Haskell. The language itself is amazing - I really like it. But I'm afraid that the dysfunctional nature of the Haskell ecosystem is driving me back to Erlang/OTP. OTP has proven to be industrial strength. I hope that someday (soon), Haskell will be able to claim that, as well.
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