Does it mean that the following expressions would be illegal?
if cond then do proc1; proc2 else do proc3; proc4
(case e of Just x - x 0; Nothing - False)
Unfortunately, yes.
Now one can forget about {} and use layout everywhere. He would no
longer be able to forget or he would have to split some expressions
into indented lines, even when they are unambiguous in one line.
Hmm, the `do x == y == z' case is a real trouble. Would it be not
too ugly to formalize the current common behavior as something like
"for the purposes of layout resolution, the syntax does not care
about fixity declarations"? I guess that treating them in any way at
this stage, as long as they don't reject non-associative operators,
would yield the same result... Ugly but practical.
One other possible solution is to remove the fixity resolution from the
grammar itself and describe it as a separate process post-parsing. This is
probably a good thing anyway: it matches the way most implementations work
and it would clean up the grammar.
Cheers,
Simon
