🚀 go-pugleaf

In article <1991Jan11.100048.3121@odin.diku.dk> sestoft@diku.dk (Peter Sestoft) writes:
   The main difference between Miranda (TM) and Lazy ML is the syntax.
   In Miranda the program lay-out has semantics: the off-side rule
   determines where an expression ends, whereas (Lazy) ML has more
   Pascal-like conventions, using semicolons similar punctuation.  (The
   off-side rule was suggested by Peter Landin in the sixties).  

What is the justification for this "off-side" rule ? The idea of whitespace 
having semantics is a potential source of inscrutable bugs and, frankly 
speaking, seems to go against the grain of modern programming language
design. The concrete syntax of such a language would no longer be context-free,
let alone LR(1)/LL(1). In fact, I am hard pressed to conceptualize an
efficient tokenizing algorithm for such languages. 

Since this rule has also been incorporated into the design of Haskell, it isn't
just historical and I am sure the designers of Haskell must have had some
reason(s) for this decision. I would like to know what benefit(s) does this
rule provide a language deisgner to trade off against the parsing 
inconvenience and inelegance ? 


anurag