Do we really need to support the second case at all ?
Yes :)
Instead of
"Hello \{name()}"
it can be written to something like
() -> F."Hello \{name()}"
That deprives your callee of the opportunity to choose the formatter for
you. Whoops, now the feature is way less expressive. One of the goals
here is to enable APIs to accept TSs as parameters, and be in control of
the when and how of formatting.
I think the choice between eager and lazy should be reflected in the syntax,
Oh great, two subtly different sets of semantics. Way to overspend the
complexity budget.
