[Agda] hints on switching between Agda versions

[Andrew Pitts]

Hi Jesper.

On 17 November 2016 at 11:34, Jesper Cockx <Jesper at sikanda.be> wrote:
> This is what I noticed:
>
> If you run 'cabal install' with the option '--program-suffix=-xxx', then
> Agda will be installed under the name agda-xxx. You can then switch Agda versions using the emacs command by entering the name of the binary.

Thanks for that tip, which sounds good. I currently have Agda-2.5.1.1
installed and I want to install the development version (that's
2.6.0-something, I guess). So following instructions at
<http://wiki.portal.chalmers.se/agda/agda.php?n=Main.Download> and
then at <https://github.com/agda/agda/blob/master/README.md#installing-agda>
I have typed the following at a command prompt:

git clone https://github.com/agda/agda.git
cd agda
cabal update


and then using your tip

cabal install --program-suffix=-2.6.0


and cabal says

Resolving dependencies...
In order, the following would be installed:
fail-4.9.0.0 (via: Agda-2.6.0) (new package)
gitrev-1.2.0 (via: Agda-2.6.0) (new package)
ieee754-0.7.9 (via: Agda-2.6.0) (new package)
murmur-hash-0.1.0.9 (via: Agda-2.6.0) (new package)
regex-tdfa-1.2.2 (via: Agda-2.6.0) (new package)
transformers-compat-0.5.1.4 (via: Agda-2.6.0 tagged-0.8.5
equivalence-0.3.1) (new version)
equivalence-0.3.1 (via: Agda-2.6.0) (reinstall) (changes:
transformers-compat-0.4.0.4 -> 0.5.1.4)
tagged-0.8.5 (via: semigroups-0.18.2) (new package)
semigroups-0.18.2 -bytestring-builder (via: Agda-2.6.0) (new package)
Agda-2.6.0 (new version)
cabal: The following packages are likely to be broken by the reinstalls:
Agda-2.5.1.1
Agda-2.5.1
Agda-2.4.2.5
Use --force-reinstalls if you want to install anyway.

and I'm not sure I really want to run

cabal install --program-suffix=-2.6.0 --force-reinstalls


in case cabal is right and my Agda-2.5.1.1 gets screwed up.

Am I just being too faint hearted?

Andy