Fragile build failure(s) using --flag=-tagged in dependencies

[recursion-ninja]

I attempted to build the keys-3.12.3 package with the following cabal.project file:

constraints:
     semigroupoids -tagged,

This results in a compilation error during the package build process:

Building library for keys-3.12.3..
[1 of 1] Compiling Data.Key

src/Data/Key.hs:823:10: error: [GHC-39999]
    • No instance for ‘Traversable1 (Tagged a)’
        arising from the superclasses of an instance declaration
    • In the instance declaration for ‘TraversableWithKey1 (Tagged a)’
    |
823 | instance TraversableWithKey1 (Tagged a) where

Perhaps the keys package should add flags to mirror those in semigroupoids in order to allow a smaller dependency footprint. The containers flag can probably be elided, leaving the following:

• flag comonad
• flag contravariant
• flag distributive
• flag tagged
• flag unordered-containers

I know that this package is "pseudo-depreciated," but there are enough reverse dependencies (7809 indirect) that I think this usability enhancement would be worth the modest investment.

[RyanGlScott]

I'd accept a PR that does this, but I doubt that I will have the energy to do this myself.

[recursion-ninja]

I'd accept a PR that does this, but I doubt that I will have the energy to do this myself.

No problem, see #26 !