mokus0

Yea, that constraint is there solely for the shortcut of evaluating at zero, which happens (perhaps surprisingly) often in practice. A more general form sounds like a useful addition, though...

I don't think I have time to look too closely at this right now, but I like the idea. One additional suggestion would be to insert the 'source' parameter as...

Cool, I'd be happy to include those. Thanks!

Yes, I believe you're right. Upon thinking about this particular case I realize I've been internally using a different heuristic from what I stated in the comments - that the...

I have not measured performance, but the underlying implementation started as a direct copy of `Data.Map` from `containers` with the types changed. It has not, generally, been kept up to...

Ah, sorry I read the types in your GADT too quickly so my examples for the entries that you can store are wrong, but the gist is correct. Better example...

See also the `dependent-sum-template` package which, if you don't mind using TH, will derive the required `GCompare` instance (and others) for you.

It seems like it should also be possible without modifying DSum, by using a type that wraps a key and adds the context - something like: data Constrained c k...