On 26/11/2009 11:50, Ian Lynagh wrote:
Wed Nov 25 15:19:01 PST 2009 Ian Lynagh<[email protected]>
* Fix a bug in alternative layout rule
M ./compiler/parser/Lexer.x +1
Great that you've implemented this. Are you planning to do a proposal
for Haskell 2011?
I recall there were a few examples that this rule doesn't cope with:
> g = (let x, y :: Int; (x,y) = (1,2) in x, 3)
There's no way to tell that the first comma should not close the layout
introduced by the 'let', but the second one should.
> f xs = [ do x | x <- xs ]
here, the vertical bar should close the do, but it doesn't.
Probably would be a good idea to add these to the test suite so we don't
forget about them.
It doesn't particularly bother me that the simpler rule can't handle
some of the obscure cases. What bothers me more is that I'm not sure
that the proposed rule is more understandable as a specification. It is
definitely easier to implement, but we need a simple way to explain
layout to the programmer.
Cheers,
Simon
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