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From: billk@hawk.cs.ukans.edu (Bill Kinnersley)
Newsgroups: comp.lang.misc
Subject: Re: Runtime Polymorphism -- To Have and Have Not (Par
Message-ID: <1991Mar5.214727.8630@hawk.cs.ukans.edu>
Date: 5 Mar 91 21:47:27 GMT
References: <559@coatimundi.cs.arizona.edu>
Organization: University of Kansas Computer Science Dept
Lines: 20

In article <559@coatimundi.cs.arizona.edu> gudeman@cs.arizona.edu 
  (David Gudeman) writes:
: Runtime polymorphism (or runtime typing, or dynamic typing) means that
: identifiers in a language do not have types that are fixed at compile
: time, they can reference values of different types at different times
: in the program.  Languages with runtime polymorphism include Lisp,
: Smalltalk, Icon, and Prolog.
: 
Runtime polymorphism is one of the worst features of Smalltalk and Icon.

In Smalltalk, people miss the typing so much that they name all of their
variables "anObject" or aNumber" to make up for it, thus forgoing the
opportunity to use meaningful names.

And in Icon, the absence of typing has led to an incredible proliferation
of operators.  Since the variables are polymorphic, the operators must all
be monomorphic.  It's entirely the operator's responsibility to decide 
whether to compare two variables as numbers (=) as strings (==) or as 
values (===).  Thus we get monstrous operations like >>=:= and --:= 
and |||:= and ~===:= that no one can remember.