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

[Manuel M T Chakravarty]

Based on the feedback received on the ”instance force” proposal

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

I conclude that the committee has decided to reject that proposal in its current form.

In summary, we agree that the proposal tries to address a real problem, namely

(1) to add additional constraints to simplify diagnostics and type queries (especially for teaching) as well as

(2) specify a local default for classes like ’IsString’.

However, we don’t think that the proposed mechanism is the right one to address this problem, and we should try to find a better solution. In summary the power-to-weight ratio of the proposal is not sufficient; specifically,

* Problem (1) might be solved better outside of the language (e.g., with a compiler option or similar);

* Problem (2) only seems to be solved partially; and

* there remain questions about details concerning the type system and import/exports.

Manuel