Independently of the encoding question, we should have another SRFI
that specifies how the Scheme reader handles "#!" directives. I am
thinking of a parameter object bound to a procedure that is called
with the port and the s-exp following the "#!" directive whenever the
reader encounters a "#!" directive. The procedure should be able to
tail-call a success or a failure procedure. On such a SRFI, we can
portably build many reader extensions.This SRFI should also expose a
way to inspect and modify the state of ports (in particular whether
case-folding is enabled, but also being able to access column and row
counters makes sense).