Add instance Foldable1 for Field, FieldLine, SectionArg and Name

[Bodigrim]

I've been experimenting with things and it seems having instance Foldable1 would be helpful: it allows to express that any Field has at least one annotation and provides for ways to collect a non-empty list of all of them.

[Bodigrim]

Rebased and added since annotations.

[phadej]

It would be great if Cabal-syntax (conditionally) depended on https://hackage.haskell.org/package/functor-classes-compat, and have Foldable1 instances for all base versions. Foldable1 is there in base for bootstrap GHCs (9.6 and 9.8), that wont add an extra boot dependency.

[andreabedini]

It would be great if Cabal-syntax (conditionally) depended on https://hackage.haskell.org/package/functor-classes-compat, and have Foldable1 instances for all base versions. Foldable1 is there in base for bootstrap GHCs (9.6 and 9.8), that wont add an extra boot dependency.

Let me repeat this in my own words. You are saying that we can affort (conditional) extra dependencies to support compiling with already released versions of GHC. In other words, Cabal and Cabal-syntax have to be able to compile with only the boot packages of the GHC version to come.

Call me stupid, I never thought of this.

[phadej]

Yes, see e.g. https://hackage.haskell.org/package/Cabal-3.6.0.0/dependencies

Depends on semigroups for real Semigroup, tagged for Proxy and void for Void, which all since have been in base.

Now these compat dependencies have been dropped as base lower bound has been raised.

EDIT: ... in particular Cabal may itself start using Foldable1 stuff, if found fit, e.g. add Foldable1s head to its internal prelude.