Permitting trailing commas for record syntax ADT declarations

[Alexander Berntsen]

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Friends,

I have a commit that allows for trailing and leading commas in record
updates, and it works fine. I think I now have gotten the hang of how
the parser is structured and generally works. GHCi output with my patch:

λ data Foo a b = MkFoo {foo :: a, bar :: b} deriving (Show)
λ (MkFoo {,foo = 2, bar = 3,}) {,foo=3,}
MkFoo {foo = 3, bar = 3}

I am happy to have a stab at all the other requests in this thread. I
will make small commits so that we can cherry-pick the ones we want.


We need to decide if we're going to sneak this into HEAD, or introduce
a language pragma (or one per structure that permits it). My vote goes
for the first-mentioned route, as this should be non-breaking changes
(if I do them correctly). Please cast your vote on the matter. :-]
- -- 
Alexander
alexander at plaimi.net
https://secure.plaimi.net/~alexander
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