Jon Pretty

Yeah, `cloc` says 45 LoC. I'm collating the values in an untyped Map, so the casts are necessary. As for the unchecked variance, it's on a phantom type. Excuses, excuses...

Doesn't look phantom to me...

Oh yeah... caught in the lie! ;) But I meant that the `T` is inferred from the instance `field`, and that `T`, LUBed with other `T`s, helps to infer a phantom type, while the instance `field` is quickly raised to a `BaseKey`... and everything is fine because of erasure...

Clever or too clever? Also, could it be made more obviously correct?

Not sure. I've been playing around with inferring types through variance for a while. I don't like the use of implicits, especially. And maybe use-site variance (i.e. bounded existentials) might work better...

Alternatively, given(a, b, c).propagate(d) { ... } could be replaced with (a & b & c).propagate(d) { ... } without the @ uv or implicits. WDYT?

That's symbolic, so also not good. Maybe I'll get a chance to play with it today.

Fair warning: you'll need to compile Mercator first, which Pyroclastic depends on. I also discovered that dotc does not infer implicit function types the same as if they're explicit lambdas at the callsite, which is problematic. Best to use scalac until I work that out.