Depend on semigroups

[LightAndLight]

Conditional dependency on semigroups causes some problems for tools that don't know now to deal with ifs in cabal files. I can't build hegdgehog on the ghc7102 or ghc7103 package sets, because the tools don't know how to account for the conditional dependency. It's okay to just always depend on semigroups - see https://qfpl.io/posts/semigroups/

Please squash this PR when you merge it :)

[LightAndLight]

I'm not sure why the tests have failed. I'll look into it later

[gwils]

It looks like the jobs timed out.

[thumphries]

That's interesting, which tool fails to understand Cabal files? cabal2nix or something? Does that cause problems more widely? Lots of packages use conditionals...

This seems harmless, we should probably merge it given the additional context.

(I don't have the perms, you will have to wait a little longer)

[nhibberd]

It's okay to just always depend on semigroups

This is still adding a redundant dependency for > 8

[LightAndLight]

@thumphries Yeah, it's cabal2nix. It currently just ignores conditional dependencies.
@nhibberd Okay. Is one of the goals of this project to minimize the number of external dependencies? I use GHC8+, and the thought of an extra dependency doesn't bother me.

[thumphries]

Yeah, it's cabal2nix. It currently just ignores conditional dependencies.

If this is the case it's broken, that situation is kinda untenable. Could this be fixed on the nix / pkgs side by editing the derivation? Is that the intended usage pattern?

In any case this is a Cassava kind of situation, we'll merge this to resolve it, just waiting on some messed up repo permissions to do so.

[LightAndLight]

In any case this is a Cassava kind of situation

Yeah I guess it is, although I wouldn't kick up such a fuss if you said no ;)

[thumphries]

Sorry that took so long. Perms sorted now