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From: wg@opal.cs.tu-berlin.de (Wolfgang Grieskamp)
Newsgroups: comp.lang.misc
Subject: Re: Dynamic typing (part 31,497)
Message-ID: <3093@opal.cs.tu-berlin.de>
Date: 17 Apr 91 20:43:15 GMT
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gudeman@cs.arizona.edu (David Gudeman) writes:

 >							   If you
 >associate type information with a value at runtime then you have
 >dynamic typing.

I have heard of this definition before, but I think its to weak.
For instance, to implement C++ virtual messages, you have to add type
information to values. (If C++ was classified as a dynamical typed
language in the course of this discussion, I must apologize.)

To implement Haskells type classes (which is surely statically typed)
you dont have to add type information to values, but at least
to functions performing computations with these values. Its
an interesting observation that the restrictions of Haskell which
dont allow the usage of "heterogeneous" lists are caused to the fact that 
type information is associated only with values passed to functions 
but not with values stored in data types. This seems to be quite 
unnaturaly in a framework based on the lambda calculus, where
data types can be expressed through higher-order functions. 

--
Wolfgang Grieskamp 
wg@opal.cs.tu-berlin.de tub!tubopal!wg wg%opal@DB0TUI11.BITNET