shithub: MicroHs

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Add Data.Dynamic

--- a/lib/AllOfLib.hs

+++ b/lib/AllOfLib.hs

@@ -18,6 +18,7 @@

 import Data.Complex

 import Data.Constraint

 import Data.Double

+import Data.Dynamic

 import Data.Either

 import Data.Enum

 import Data.Eq

@@ -51,6 +52,7 @@

 import Data.Semigroup

 import Data.STRef

 import Data.Tuple

+import Data.Typeable

 import Data.TypeLits

 import Data.Void

 import Data.Word

--- /dev/null

+++ b/lib/Data/Dynamic.hs

@@ -1,0 +1,30 @@

+module Data.Dynamic(

+  Typeable(..),

+  Dynamic,

+  toDyn,

+  fromDyn, fromDynamic,

+  dynApply, dynApp,

+  ) where

+import Prelude

+import Data.Proxy

+import Data.Typeable

+import Unsafe.Coerce

+

+data Dynamic = D TypeRep Any

+

+toDyn :: forall a . Typeable a => a -> Dynamic

+toDyn a = D (typeOf a) (unsafeCoerce a)

+

+fromDyn :: forall a . Typeable a => Dynamic -> a -> a

+fromDyn d a = fromMaybe a $ fromDynamic d

+

+fromDynamic :: forall a . Typeable a => Dynamic -> Maybe a

+fromDynamic (D tr a) | tr == typeRep (Proxy :: Proxy a) = Just (unsafeCoerce a)

+                     | otherwise = Nothing

+

+dynApp :: Dynamic -> Dynamic -> Dynamic

+dynApp f a = fromMaybe (error "Dynamic.dynApp") $ dynApply f a

+

+dynApply :: Dynamic -> Dynamic -> Maybe Dynamic

+dynApply (D ftr f) (D atr a) = fmap f $ funResultTy ftr atr

+  where f rtr = D rtr ((unsafeCoerce f) a)

-- 

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