|[2 earlier articles]|
|Re: Example interpreter C email@example.com (Laurence Finston) (2005-08-21)|
|Re: Example interpreter C firstname.lastname@example.org (George Neuner) (2005-08-24)|
|Re: Example interpreter C email@example.com (Laurence Finston) (2005-09-07)|
|Re: Example interpreter C firstname.lastname@example.org (Ivan Boldyrev) (2005-09-10)|
|Re: Example interpreter C email@example.com (Laurence Finston) (2005-09-14)|
|Re: Example interpreter C firstname.lastname@example.org (Ivan Boldyrev) (2005-09-17)|
|Re: Lisp variables, was Example interpreter C email@example.com (Laurence Finston) (2005-09-22)|
|Re: Lisp variables, was Example interpreter C firstname.lastname@example.org (Julian Stecklina) (2005-09-25)|
|From:||Laurence Finston <email@example.com>|
|Date:||22 Sep 2005 23:40:03 -0400|
|References:||05-08-055 05-08-062 05-08-073 05-08-084 05-09-025 05-09-036 05-09-051 05-09-066|
On Sat, 17 Sep 2005, Ivan Boldyrev wrote:
> GCL is bad example: it is not standard-conforming :)
Thanks for the information. If I ever document this, I won't call it
"LISP-like behavior". However, it is the behavior that I would
implement, if were to go back and rewrite my grammar. I'm sorry to
hear that this behavior doesn't conform to the LISP standard. I found
it very convenient.
In GNU 3DLDF, as in Metafont, this does work for variables of
* a := 324.54;
* show a;
* numeric a;
* show a;
The declaration of `a' as a `numeric' wipes out the old value.
The behavior in Metafont is slightly different in that an unknown
`numeric' doesn't have any value. In 3DLDF, it's not really
unknown once it's been named.
I think it would have been perfectly easy to implement the same behavior
for other data types: `points', `transforms', `paths', etc. I'm not sure
how easy it would be to change it after the fact, though.
The arguments I know of against this behavior are stylistic, and I
disagree with them. I know of no technical reason for not implementing
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