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Diffstat (limited to 'docs/users_guide/exts/static_pointers.rst')
| -rw-r--r-- | docs/users_guide/exts/static_pointers.rst | 12 |
1 files changed, 6 insertions, 6 deletions
diff --git a/docs/users_guide/exts/static_pointers.rst b/docs/users_guide/exts/static_pointers.rst index e142b14be2..d6f5e55a73 100644 --- a/docs/users_guide/exts/static_pointers.rst +++ b/docs/users_guide/exts/static_pointers.rst @@ -51,18 +51,18 @@ All of the following are permissible: :: inc :: Int -> Int inc x = x + 1 - ref1 = static 1 + ref1 = static 'a' ref2 = static inc ref3 = static (inc 1) ref4 = static ((\x -> x + 1) (1 :: Int)) - ref5 y = static (let x = 1 in x) - ref6 y = let x = 1 in static x + ref5 = static (let x = 'a' in x) + ref6 = let x = 'a' in static x While the following definitions are rejected: :: ref7 y = let x = y in static x -- x is not closed ref8 y = static (let x = 1 in y) -- y is not let-bound - ref8 (y :: a) = let x = undefined :: a + ref9 (y :: a) = let x = undefined :: a in static x -- x has a non-closed type .. note:: @@ -99,7 +99,7 @@ expression is overloaded to allow lifting a ``StaticPtr`` into another type implicitly, via the ``IsStatic`` class: :: class IsStatic p where - fromStaticPtr :: StaticPtr a -> p a + fromStaticPtr :: Typeable a => StaticPtr a -> p a The only predefined instance is the obvious one that does nothing: :: @@ -111,7 +111,7 @@ See :base-ref:`GHC.StaticPtr.IsStatic`. Furthermore, type ``t`` is constrained to have a ``Typeable`` instance. The following are therefore illegal: :: - static show -- No Typeable instance for (Show a => a -> String) + static id -- No Typeable instance for (a -> a) static Control.Monad.ST.runST -- No Typeable instance for ((forall s. ST s a) -> a) That being said, with the appropriate use of wrapper datatypes, the |