> Or just drop the ". args" convenience feature, and always return
> whatever's there, lambda or not.  Based on whatever is specified in
> the SRFI's use of lambdas for localization, or the conventions of the
> error-set collection, the user, IDE, whatever then calls the lambda
> with the correct arguments, if any.

That may end up being the best idea in the end. Thanks for being an
advocate of simplicity.

> Making the API regular is more important than a bit of convenience,
> especially given how fundamental lambdas are to Scheme.

That's true, and regularity is a particular virtue of Scheme as compared
to most other languages, even to other Lisps.

However, the ubiquity of lambdas also means that they are quite cheap
both syntax- and efficiency-wise so we shouldn't worry too much about
sprinkling them around.