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From: Paul_Abrahams%Wayne-MTS@UM.CC.UMICH.EDU
Newsgroups: comp.lang.icon
Subject: Uses of dynamic typing
Message-ID: <270675@Wayne-MTS>
Date: 17 Nov 90 01:47:38 GMT
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As I mentioned in an earlier posting, I'm working on the design of SPLASH,
a Systems Programming Language for Software Hackers.  A question came up about
how people use Icon's dynamic typing.  In Icon the type of a variable isn't
determined until you assign something to it, and even then it can change. 
That's in contrast with other languages of the Algol/Pascal/Ada/C sort, in
which every variable has a declared type. 
 
My question is: how important is this flexibility for Icon programming, and
how do people utilize it?  There's one place where it clearly pays off: the
possibility of writing a procedure that prints its argument no matter what the
type of the argument.  The fact that you can't write the C printf function in
standard C shows why you want this.  But aside from printing arguments and
writing out their storage, I haven't been able to think of other operations
that use the flexibility.  Interestingly, sorting isn't one of those examples,
since not all data types have a natural ordering relation and even for those
that do, you use different operators in Icon (`<' for numbers, `<<' for
strings.) 
 
Examples, anyone--particularly from programs that do something rather than
just prove something?
 
Paul Abrahams
abrahams%wayne-mts@um.cc.umich.edu