From josef.svenningsson at gmail.com  Sun Aug  2 15:03:27 2015
From: josef.svenningsson at gmail.com (Josef Svenningsson)
Date: Sun, 02 Aug 2015 15:03:27 +0000
Subject: simultaneous ghc versions
In-Reply-To: <20150801063138.246d3697079385296f431930@mega-nerd.com>
References: <CACbaDy4-n9G19nRfjGv4MS4a_q=VVDATSugK0ZKvbms0T0mXSg@mail.gmail.com>
 <20150801063138.246d3697079385296f431930@mega-nerd.com>
Message-ID: <CAGF=PZ+prtW4mDuBo1pM=LsO8JY-6+7p9CDB0oRChOW+siMD-A@mail.gmail.com>

On Fri, Jul 31, 2015 at 10:31 PM Erik de Castro Lopo <mle+hs at mega-nerd.com>
wrote:

> I maintaing multiple versions of GHC on all the machines I use regularly
> for Haskell development. I have:
>
> * ghc-7.6.3 installed under /usr/lib/ghc-7.6/
> * ghc-7.8.4 installed under /usr/lib/ghc-7.8/
> * ghc-7.10.2 installed under /usr/lib/ghc-7.10/
>
> To switch between versions all I need to do is modify $PATH
> to remove say /usr/lib/ghc-7.6/bin and add /usr/lib/ghc-7.10/bin.
> This lets me have two terminal window side by side with different
> versions of GHC.
>
> I actually have a shell function to to do this PATH mangling. I can
> document this more fully if anyone is interested.
>
>
I have a similar setup where I install different versions of GHC in
different directories. But I use GNU stow[1] to create and remove symlinks
in /usr/local/* so that I can use one version of GHC as the default.

[1] https://www.gnu.org/software/stow/

Josef
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From alexander at plaimi.net  Mon Aug  3 14:04:58 2015
From: alexander at plaimi.net (Alexander Berntsen)
Date: Mon, 03 Aug 2015 16:04:58 +0200
Subject: simultaneous ghc versions
In-Reply-To: <CACbaDy4-n9G19nRfjGv4MS4a_q=VVDATSugK0ZKvbms0T0mXSg@mail.gmail.com>
References: <CACbaDy4-n9G19nRfjGv4MS4a_q=VVDATSugK0ZKvbms0T0mXSg@mail.gmail.com>
Message-ID: <55BF750A.7090801@plaimi.net>

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On 31/07/15 20:10, Evan Laforge wrote:
> Come to think of it, shouldn't ghc include this, instead of
> everyone creating their own shell scripts by hand?
I don't think so. This is usually done in the userland -- at least in
GNU+Linux distributions.

And as mentioned, cabal handles it already.
- -- 
Alexander
alexander at plaimi.net
https://secure.plaimi.net/~alexander
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From allbery.b at gmail.com  Mon Aug  3 14:17:46 2015
From: allbery.b at gmail.com (Brandon Allbery)
Date: Mon, 3 Aug 2015 10:17:46 -0400
Subject: simultaneous ghc versions
In-Reply-To: <55BF750A.7090801@plaimi.net>
References: <CACbaDy4-n9G19nRfjGv4MS4a_q=VVDATSugK0ZKvbms0T0mXSg@mail.gmail.com>
 <55BF750A.7090801@plaimi.net>
Message-ID: <CAKFCL4XRmdxD7LHwLRm+Nu=0E=umMWQF4ZmQb5k37_nPtT0Khg@mail.gmail.com>

On Mon, Aug 3, 2015 at 10:04 AM, Alexander Berntsen <alexander at plaimi.net>
wrote:

> On 31/07/15 20:10, Evan Laforge wrote:
> > Come to think of it, shouldn't ghc include this, instead of
> > everyone creating their own shell scripts by hand?
> I don't think so. This is usually done in the userland -- at least in
> GNU+Linux distributions.
>

More to the point, various distribution methods already include such things
(e.g. NixOS, Debian's alternatives system, MacPorts' "port select") plus
there are various mechanisms for implementing this on an ad-hoc basis (GNU
stow, environment modules, etc.). Downstream packages implementing their
own versions of this except speicifically on an opt-in basis (e.g.
configure option) tend to interfere with these and complicate inclusion
into existing package systems.

-- 
brandon s allbery kf8nh                               sine nomine associates
allbery.b at gmail.com                                  ballbery at sinenomine.net
unix, openafs, kerberos, infrastructure, xmonad        http://sinenomine.net
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