Getting started
James J. Besemer
jb at cascade-sys.com
Sat Sep 28 04:24:54 EDT 2002
Adam Taylor wrote:
>Python is in the same square as Lisp (which I mentioned). So is Perl.
>At least using this terminology... ;)
>
Agreed.
>Okay, that's true, he does define weakly-checked only in terms of
>statically checked languages, which I hadn't appreciated:
>
>But the clear generalization of this (it seems to me) is to define
>weakly checked languages as languages in which some unsafe operations
>are detected and some are not detected. In other words, just delete the
>word "statically" from the last sentence in the quote above.
>
Exactly. I think I said as much earlier, though not as succinctly.
>Of course, it doesn't sound like any existing languages are both
>dynamically typed and weakly checked (and I can't think of any myself):
>
I recall a Lisp implementation from long ago that did not distinguish
between integers and machine addresses. When applying a function to an
arg list, if the function name evaluated to a number the interpreter
blithely JSRed to that address. This was a Feature, in that it was how
system built-ins were linked with the higher level stuff. User code did
not normally do this and it was not a big issue in practice. However it
WAS a loophole that allowed type errors to occur, as it allowed code to
jump to any random address in the system.
But I think the generalization holds for most dynamic languages.
Regards
--jb
--
James J. Besemer 503-280-0838 voice
2727 NE Skidmore St. 503-280-0375 fax
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