What exactly are you proposing as an alternative rule? If you're suggesting that _any_ line at the same level of indentation as the previous line be treated as a continuation of that line, then how would one go about indicating that a line is _not_ a continuation of the previous line? I don't see any fundamental reason why this couldn't be handled like
On the other hand, if you're suggesting that only certain things be recognized as being a continuation of the previous line (e.g., guard clauses), then it seems to me that you're replacing a brain-dead simple and straightforward rule with one that is inherently more complex and thus more likely to cause angst among beginners. For the most part, beginners can get by using only a superficial understanding of the layout rule. They only have to worry about the
2007/7/27, Steve Schafer
if condition then consequent else alternative which works well enough until you try to use it inside a do block. Amending the rules to allow this usage would arguably decrease "angst among beginners" with no appreciable impact on the overall complexity of the language. I see my original example as belonging to this same category of sensible things that are disallowed for no apparent reason.
Or are you proposing to get rid of layout altogether and rely on punctuation?
I just can't think of a rule that would be easier to understand (and quicker to assimilate) than the current one. Clearly, eliminating layout altogether would simplify things greatly. And yet, I assume would do want to keep it around even at the cost of increased complexity. Why is that I wonder? What is far less clear however is that adding a few optional semicolons to the grammar in order to accommodate different programming styles would impose an incommensurate intellectual burden on programmers who paradoxically don't mind the occasional detour through category theory in their "hello world" programs.