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Re: dynamic vs. static typing

On 2003-11-24T08:53:56-0800, Steve Dekorte wrote:
> Yes, and the only union may be introspection methods. In which case we 
> might be able to validly send any method that the introspection API 
> reveals to us, even though our type system (which restricted us to the 
> introspection methods) wouldn't allow it.

Maybe -your- type system wouldn't allow it, but mine does:

    import Char (ord)

    data Union = A Char | B Int

    unionToInt :: Union -> Int
    unionToInt (A c) = ord c
    unionToInt (B i) = i

Here I send the "ord" message, which only characters respond to, to a
value that introspection reveals at runtime is a character rather than
an integer.  This has already been explained on this thread at

    Message-ID: <20031120022752.GB14598@proper.eecs.harvard.edu>

See also dynamic_cast in C++.


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