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| Data.Dynamic | | Portability | portable | | Stability | experimental | | Maintainer | libraries@haskell.org |
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| Description |
The Dynamic interface provides basic support for dynamic types.
Operations for injecting values of arbitrary type into
a dynamically typed value, Dynamic, are provided, together
with operations for converting dynamic values into a concrete
(monomorphic) type.
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| Synopsis |
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| Documentation |
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| module Data.Typeable |
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| The Dynamic type
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| data Dynamic |
A value of type Dynamic is an object encapsulated together with its type.
A Dynamic may only represent a monomorphic value; an attempt to
create a value of type Dynamic from a polymorphically-typed
expression will result in an ambiguity error (see toDyn).
Showing a value of type Dynamic returns a pretty-printed representation
of the object's type; useful for debugging.
|  Instances | |
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| Converting to and from Dynamic
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| toDyn :: Typeable a => a -> Dynamic |
Converts an arbitrary value into an object of type Dynamic.
The type of the object must be an instance of Typeable, which
ensures that only monomorphically-typed objects may be converted to
Dynamic. To convert a polymorphic object into Dynamic, give it
a monomorphic type signature. For example:
toDyn (id :: Int -> Int)
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| fromDyn |
| :: Typeable a | | | => Dynamic | the dynamically-typed object
| | -> a | a default value
| | -> a | returns: the value of the first argument, if
it has the correct type, otherwise the value of
the second argument.
| | Converts a Dynamic object back into an ordinary Haskell value of
the correct type. See also fromDynamic.
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| fromDynamic |
| :: Typeable a | | | => Dynamic | the dynamically-typed object
| | -> Maybe a | returns: Just a, if the dynamically-typed
object has the correct type (and a is its value),
or Nothing otherwise.
| | Converts a Dynamic object back into an ordinary Haskell value of
the correct type. See also fromDyn.
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| Applying functions of dynamic type
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| dynApply :: Dynamic -> Dynamic -> Maybe Dynamic |
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| dynApp :: Dynamic -> Dynamic -> Dynamic |
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| Produced by Haddock version 0.7 |
