Path: utzoo!attcan!uunet!lll-winken!lll-tis!helios.ee.lbl.gov!nosc!ucsd!rutgers!bellcore!tness7!tness1!sugar!ficc!karl
From: karl@ficc.uu.net (karl lehenbauer#)
Newsgroups: comp.lang.forth
Subject: type checking
Message-ID: <1389@ficc.uu.net>
Date: 1 Sep 88 16:26:40 GMT
References: <8808121826.AA23206@jade.berkeley.edu> <1575@crete.cs.glasgow.ac.uk> <535@hudson.acc.virginia.edu>
Organization: Ferranti International Controls
Lines: 33

In article <535@hudson.acc.virginia.edu>, pmy@vivaldi.acc.virginia.edu (Pete Yadlowsky) writes:
> Baggage, baggage and more baggage. Type checking?! *gag* I don't want
> some uppity compiler protecting me from myself and telling me how I
> may and may not use my computer. That stuff's fine for beginners, but
> when it's time to cut loose and actually put the machine to work...

Oh, please!  I once spent days finding a bug in a Forth program where a guy
had done a store (rather than a c-store) into a CVARIABLE, clobbering an
adjacent data byte (1802 polyForth with separate symbol table)  Most of
my C bugs seem to be type conflicts in function calls, incorrect number of
arguments and such, which ANSI X3J11 addresses at last.  I expect that the
ANSI C compiler is going to catch 90% of my bugs.  Don't get me wrong, I like 
Forth a lot, but in Forth when one gets the number of arguments wrong, like
in a loop, one typically blows the stack and crashes the machine.  Eliminating 
type checking from the language leaves it to the programmer, in FORTH a word 
for every operation for every data type, and Forth (and FORTRAN where one has to
kludge pointers as array indexes and such to get around not having data types)
will merrily compile bogus code that a type-checking compiler would gritch at, 
leaving it to the programmer to debug.

Again, I am not constrained by type checking; type checking catches bugs;
type checking finds and notifies the programmer of *impossible* usages of
data.  Although it is "telling me how I may and may not use my 
computer," it is never appropriate to do word writes into byte fields, use 
floating point numbers as pointers, pass ints to routines that want pointers 
to floats &c &c &c  

(I just have to keep harping.  Consider the DO..LOOP, IF..THEN, BEGIN..REPEAT 
security in Forth that insure control structures are properly nested.  Hey,
that's the machine telling me what to do!?  If I want to write a routine with
a LOOP that doesn't have a DO, that's my business. :-)
-- 
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