1. If an end-of-line sequence immediately follows the indentation and the indentation length is nonzero:
 a. If the indentation contains â!â, it is an error; an implementation SHOULD reject it.
"""
Why error rather than allowing it as either ignored or terminating line?
I can see how punting the question "is ! empty" simplifies the spec, but it may be a missed opportunity.
Once you prefix a block with !, it seems to me there is no reason to additionally require a comment â "! ;" (or other workarounds) â to express ignored vertical whitespace.
Isn't this the cleanest thing possible:
define long-func(x)
 let ((foo bar(x)))
 ! do stuff
 ! ...
 !
 ! more stuff
 ! ...
In any case, I didn't find this discussed in the rationale.
--
Beni Cherniavsky-Paskin