Simon, have you given any thought to how this interacts with type system
extensions, in particular with GADTs and type families? The proposal relies on
being able to "find the type" of a term but it's not entirely clear to me what
that means. Here is an example:
foo :: F Int -> Int
foo :: Int -> Int
bar1 :: Int -> Int
bar1 = foo
bar2 :: Int ~ F Int => Int -> Int
bar2 = foo
IIUC, bar1 is ok but bar2 isn't. Do we realy want to have such a strong
dependency between name lookup and type inference? Can name lookup be specified
properly without also having to specify the entire inference algorithm?
Another example: suppose we have
data T a where
TInt :: T Int
TBool :: T Bool
foo :: T Int -> u
foo :: T Bool -> u
bar :: T a -> u
bar x = case x of
TInt -> foo x
TBool -> foo x
Here, (foo x) calls different functions in the two alternatives, right? To be
honest, that's not something I'd like to see in Haskell.
Roman
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