Thomas Jäger [EMAIL PROTECTED] writes:
I believe there may be some nasty interactions with generalized
newtype-deriving, since we can construct two Leibniz-equal types which
are mapped to different types using fundeps:
class Foo a where
foo :: forall f. f Int - f a
instance Foo
Simon,
I believe there may be some nasty interactions with generalized
newtype-deriving, since we can construct two Leibniz-equal types which
are mapped to different types using fundeps:
class Foo a where
foo :: forall f. f Int - f a
instance Foo Int where
foo = id
newtype Bar =
2005 13:48
| To: haskell-cafe@haskell.org
| Subject: [Haskell-cafe] Functional dependencies and type inference
|
| Hello
|
| I am having problems with GHC infering functional dependencies related
| types in a too conservative fashion.
|
| class Imp2 a b | a - b
| instance Imp2 (Foo a) (Wrap
Hello,
On 8/11/05, Simon Peyton-Jones [EMAIL PROTECTED] wrote:
... Here is a boiled down version, much simpler to
understand.
module Proxy where
class Dep a b | a - b
instance Dep Char Bool
foo :: forall a. a - (forall b. Dep a b = a - b) - Int
Hello
I am having problems with GHC infering functional dependencies related
types in a too conservative fashion.
class Imp2 a b | a - b
instance Imp2 (Foo a) (Wrap a)
newtype Wrap a = Wrap { unWrap :: a }
data Foo a = Foo
data Proxy (cxt :: * - *)
foo :: Imp2 (ctx c) d = Proxy ctx -
