Macro functions applied to "tuples" results in type error

[edsko]

Something like

#define ARGS 1,2
#define SUM(X,Y) X + Y

will result in a type error, because we infer a curried type for SUM, which can then not be applied to the tuple. Agreed with the client that we'd record this as a known limitation at the moment, and will come back to it if and when we have a motivating example.