roma at ro-che.info
Mon May 18 08:11:24 UTC 2015
On 18/05/15 10:57, Alan & Kim Zimmerman wrote:
> Hi all
> I am working on D836 and have the following test case
> data MaybeDefault v where
> SetTo4 :: forall v a. (( Eq v, Show v ) => v -> MaybeDefault v
> -> a -> MaybeDefault [a])
> GHC 7.10.1 regards the return type of SetTo4 as `MaybeDefault [a]`
> The question is, due to the parens, is the return type not the whole RHS?
> i.e. Similar to how in the signature
> map :: (a -> b) -> [a] -> [b]
> the first paramater is a single function.
> I am sure I am just confused here.
This is the wrong analogy, since (a -> b) in map's type is in the
The correct analogy would be the return type of
map :: (a -> b) -> ([a] -> [b])
You could argue it both ways. (But only one of them leads to the above
declaration being correct, since the function type is not an instance of
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