Hi,
If I understand correctly, the traditional defaulting rules prevent
defaulting variables with constraints like (Num a, Convertible a
Double), but the NamedDefaults proposal would allow defaulting a ~
Double in this case due to the relaxed defaulting rules in section 2.5
of the proposal:
https://github.com/ghc-proposals/ghc-proposals/blob/master/proposals/0409-exportable-named-default.rst#id2
1. Is there any plan to start implementing NamedDefaults? I saw the
comment from Simon P-J that it would not be fun to implement because it
might require orphan default declarations... so perhaps there's no plan
to implement this?
2. Would it be worth adding a separate LANGUAGE option that just
implements the relaxed defaulting rules in section 2.5? Specifically (a)
allowing variables with multiparameter constraints and (b) allowing
variables with constraints that are not in the Prelude.
3. Am I correct in assuming that the relaxed defaulting rules require
NamedDefaults to be enabled in the importing module, and not just in the
imported model?
-BenRI
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