Cabal install

[Oleg Grenrus]

Hi Simon,

my first guess is that: when working on the unsaturated type families 
paper, you did `cabal install --lib report`; or something similar. 
`report` is probably some internal library to that paper / project.

In that case, you are hitting the unfortunate cabal bug [1].

To confirm, check what is in your 
~/.ghc/x86_64-linux-8.6.5/environments/default (or similar), is some 
`package-id report-0.1.0.0-hexhash` line there? If so, the simplest fix 
is to remove that environment file.

- [1] https://github.com/haskell/cabal/issues/5888 
https://github.com/haskell/cabal/issues/5559

Cheers,
Oleg

On 30.5.2019 16.50, Simon Peyton Jones wrote:
>
> Dear friendly Cabal folk
>
> Here’s what happened to me today
>
> bash$ cabal install lhs2tex
>
> cabal: Could not resolve dependencies:
>
> [__0] next goal: report (user goal)
>
> [__0] rejecting: report-0.1.0.0 (conflict: requires 
> UnsaturatedTypeFamilies)
>
> [__0] fail (backjumping, conflict set: report)
>
> After searching the rest of the dependency tree exhaustively, these 
> were the
>
> goals I've had most trouble fulfilling: report
>
> Crumbs.  What is ‘report’?  Why does it need 
> UnsaturatedTypeFamilies?   I’m totally lost.
>
> Then, in an inspired moment, I thought to change to a different 
> directory, ~/tmp.
>
> Then quite different things happened – it downloaded and built 
> relevant libraries.
>
> I think that there just happened to be a .cabal file in the original 
> directory I was in at the time. That appears to affect what ‘cabal 
> install’ does in a truly radical way.
>
> My point is this: this is terribly confusing for the user (at least 
> for this on).   I’d be shocked if ‘apt install blah’ behaved utterly 
> differently in different directories.  I’m going to make a little 
> empty directory somewhere, and cd to it before invoking cabal in 
> future.  But that just feels like a workaround, not a solution.
>
> I’m not saying it’s wrong – just giving you a data point that it had 
> one user completely stumped
>
> Simon
>
>
> _______________________________________________
> cabal-devel mailing list
> cabal-devel at haskell.org
> http://mail.haskell.org/cgi-bin/mailman/listinfo/cabal-devel
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mail.haskell.org/pipermail/cabal-devel/attachments/20190530/96089b5b/attachment-0001.html>