er, i'm not sure i explained that very clearly. i ...

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[rm]

er, i'm not sure i explained that very clearly. i want to write evalNodes0 (or evalNodes1). to do that, i have to write either evalNode0 or evalNode1. in order to write evalNode0, i have to use that .map{x -> x} trick to massage the specific types returned by evaluateTermA et al, to the more general return type of evalNode0. alternatively, i could use a variance annotation to make the return type covariant (as i did with evalNode1). the problem is that the latter will cause inference problems (evalNodes1) that i don't know how to solve