[ghc-steering-committee] Proposal #23: instance force

[Manuel M T Chakravarty]

We need to decide whether we like to accept the ”instance force" proposal:

  https://github.com/ghc-proposals/ghc-proposals/pull/23

While I understand and am in favour of the motivation behind the proposal, I like to propose to reject the proposal in its current form.

My reasons are the following:

* The proposal is an ad hoc approach to adding additional type constraints to qualified types involving a specific type class.

* I am against adding the proposed ”instance force” declaration form as its *main* motivation is to simplify error messages and type signatures printed by GHCi — i.e., it is of a diagnostic and informative nature.

* Something like that does IMHO not belong into the language, but needs to be part of the configuration of the compilation system. In other words, it ought to be a, e.g., compiler option or a language pragma, but not a declaration form.

In summary, I’d like to suggest to find an alternative means to get GHC to add the additional constraints to simplify diagnostics and type queries without encumbering the language itself.

Cheers,
Manuel