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From: cs450a03@uc780.umd.edu
Newsgroups: comp.lang.misc
Subject: RE: Dynamic typing (part 3)
Message-ID: <6APR91.10183202@uc780.umd.edu>
Date: 6 Apr 91 10:18:32 GMT
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Victor Yodaiken >
Darren New      >>

>>Dynamic typing is when the type of a *variable* is unknown (and unspecified)
>>at compile time.  Any given value assigned to that variable will have
>>a type, but the variable does not restrict what types of values may
>>be assigned to it.

I just realized: that should begin "Dynamic typing is when the type of
a variable _may_ be unknown at compile time."

>Makes sense. But, then I don't believe that dynamic typing is similar
>to standard mathematical usage. In fact, it seems that the trend in
>mathematics has been towards greater use of "static typing".  The
>problem with "untyped" expressions is that they are inherently
>ambiguous. If I'm writing about semigroups and regular languages I
>must tell you when a*b is concatenation and when it is semigroup
>addition.

Here, * is a variable, and "telling me when a*b is cantenation" "and
when it is semigroup addition" are both declarations (or assignment
statements).  That can get confusing, I agree, which is a good reason
for using a separate symbol for each usage.

Raul Rockwell