But it does not blow up (or even return a proper error) if passed nonsense. So, work to be done (in particular, the default formatter without an explicit string tries way too much)
I understand the context you're coming from - that there are too many _untyped_ strings floating around with structure which is only checked when they are 'interpreted'.
I do like string interpolation tactics like "$YEAR-$MONTH-$DAY". Some languages allow string interpolation that respects the lexical environment, (so in Moonscript it would be "#{YEAR}-#{MONTH}-#{DAY}") but even without language support (a) these strings can be checked by a suitable formatter constructor and (b) allows for formatting tables.
