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From: gudeman@cs.arizona.edu (David Gudeman)
Newsgroups: comp.lang.misc
Subject: Re: Dynamic typing (part 31,497)
Message-ID: <1883@optima.cs.arizona.edu>
Date: 14 Apr 91 21:44:05 GMT
Sender: news@cs.arizona.edu
Lines: 31

In article  <8742@skye.cs.ed.ac.uk> Nick Rothwell writes:
]
]Now, using such general terms as "function" and "sequence" in a mathematical
]context, I assumed your were implying a homogeneous list. If you're assuming
]heterogeneous sequences, then the kind of mathematics you're dealing with
]gets more complicated than I assumed. I think.

Why would you assume that?  Math makes no distinction between
homogenous and heterogeneous lists.  What complication are you talking
about?  It is trivial to define a heterogeneous list in math:

Let S be the sequence beginning with S[1] defined as follows:
  if i is odd then S[i] = i
  if i is even then S[i] = {i, i-1}

It is equally trivial to define a function to act on heterogenous
elements:

Let f x be defined as follows:
  if x is an integer then x
  else if x is a set then the min element of x

All of this can be programmed directly in a language with dynamic
typing and requires extra effort in a language with static typing.
My main criterion for the expresiveness of a language is "does it let
me say what I want to directly, instead of making me work around
limitations in the language?"
--
					David Gudeman
gudeman@cs.arizona.edu
noao!arizona!gudeman