On Mon, Feb 25, 2013 at 4:11 PM, Simon Peyton-Jones
I suppose we want an instance forall k. instance Typeable (k -> *) (Proxy k)
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Yes, that looks right.****
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So the universally quantified kind variables of the tycon should end up universally quantified in the instance as well. How does this translate to the ds_tvs, ds_tys, and ds_tc_args arguments of a DerivSpec****
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My instinct is that the ds_tvs include both type and kind variables, kind variables first. The kinds of the type variables can mention the kind variables.
We don't have any type variables, we want to drop those, as we'll get those instances via the `(Typeable f, Typeable a) => Typeable (f a)` instance. In my branch, I currently get standalone deriving to give me the following for this example (tc-trace): Standalone deriving; tvs: [k] theta: [] cls: Typeable tys: [k -> *, Proxy k] Standalone deriving: class: Typeable class types: [k -> *] type: Proxy k This looks good to me. However, the generated instance is not what I think it should be (ddump-types): instance Typeable (forall (k :: BOX). k -> *) (Proxy k) The forall should be outside, as now the `k` in `Proxy k` is out of scope. I just don't know how to craft such a DerivSpec... what I have now is: DS { ds_loc = loc, ds_orig = orig, ds_name = dfun_name, ds_tvs = tvs , ds_cls = cls, ds_tys = tyConKind tycon : [mkTyConApp tycon tc_args] , ds_tc = tycon, ds_tc_args = tc_args , ds_theta = mtheta `orElse` [], ds_newtype = False }) } (I filter the type variables from the tc_args before this stage, leaving only kind variables.) Cheers, Pedro