I really like the \of proposal! It is a clean elision with \x -> case x of becoming \of I still don't like it directly for multiple arguments. One possible approach to multiple arguments is what we use for multi-argument case/alt here in our little haskell-like language, Ermine, here at S&P CapitalIQ, we allow for ',' separated patterns, but without surrounding parens to be treated as a multi argument case and alt pair. Internally we desugar our usual top level bindings directly to this representation. When mixed with the \of extension, this would give you: foo :: Num a => Maybe a -> Maybe a -> Maybe a foo = \of Just x, Just y -> Just (x*y) _, _ -> Nothing but it wouldn't incur parens for the usual constructor pattern matches and it sits cleanly in another syntactic hole. A similar generalization can be applied to the expression between case and of to permit a , separated list of expressions so this becomes applicable to the usual case construct. A naked unparenthesized , is illegal there currently as well. That would effectively be constructing then matching on an unboxed tuple without the (#, #) noise, but that can be viewed as a separate proposal' then the above is just the elision of the case component of: foo mx my = case mx, my of Just x, Just y -> Just (x*y) _, _ -> Nothing On Jul 5, 2012, at 2:49 PM, wagnerdm@seas.upenn.edu wrote:
Quoting wagnerdm@seas.upenn.edu:
Well, for what it's worth, my vote goes for a multi-argument \case. I
Just saw a proposal for \of on the reddit post about this. That's even better, since:
1. it doesn't change the list of block heralds 2. it doesn't mention case, and therefore multi-arg \of is perhaps a bit less objectionable to those who expect "case" to be single-argument 3. 40% less typing!
Can I change my vote? =) ~d
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