Documentation

Dynamic value whose content is showable. Using this type instead of Dynamic is recommended because it gives better error messages.

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.

convert a dynamically-typed method to a polymorphic method.

  fDyn :: String -> DynamicShow -> Dynamic -> IO [DynamicShow]
  fDyn = ...
  fPoly :: (Typeable a, Show a, Typeable b, Typeable c, Show c) => String -> a -> b -> IO [c]
  fPoly = castMethod fDyn
  

Convert given matcher to dynamic matcher. The dynamic matcher matches a dynamic value only if the value has the type of given matcher.

Generalizes Dynamic and DynamicShow

FromDyn a b provides a function to convert type a to type b, where b is a type whose dynamic type occurences are replaced by concrete types.

For example: FromDyn (Int, Dynamic, Maybe Dynamic) (Int, Bool, Maybe String)

ToDyn a b provides a function to convert type b to type a, where b is a type whose dynamic type occurences are replaced by concrete types.

For example: ToDyn (Int, Dynamic, Maybe Dynamic) (Int, Bool, Maybe String)

The class Typeable allows a concrete representation of a type to be calculated.