Re: [Sbcl-devel] Bug or Feature?

[Raffael C. <raf...@ma...>]

On Mar 26, 2005, at 9:05 AM, Friedrich Dominicus wrote:

> Well as
> understand this should be the same as ::isbn it's not that a " " is
> between the | and well according to LW this is interpreted as such

Just to be completely clear on this Friedrich, please note that 
Nikodemus and Brian have been talking about the empty string, *not* a 
space. In your email quoted above, you're talking about a space, *not* 
the empty string. They are telling you that there is no requirement for 
an implementation to behave as if the empty string is a nickname for 
the keyword package.

All the implementations you quote clearly have readers that  treat the 
empty string as if it were a nickname for the keyword package, so that 
::foo is read as keyword::foo, but they are saying that there is no 
guarantee in the standard that the keyword package have the empty 
string as a nickname, so there is no requirement for implementations to 
read ::foo as if it were keyword::foo. Please not that I am not 
sufficiently familiar with the reader algorithm as given in the 
standard to have any worthwhile opinion on this matter myself.

To see what is going on here is a simple transcript from LispWorks:

CL-USER 11 > (macroexpand keyword::foo)
:FOO
NIL

CL-USER 12 > (macroexpand ::foo)
:FOO
NIL

Interestingly, LispWorks claims that the keyword package has *no* 
nicknames:

CL-USER 20 > (package-nicknames 'keyword)
NIL

Ditto OpenMCL

So technically, this behavior is not due to the keyword package having 
"" as a nickname (because the keyword package has no nicknames in 
LispWorks, ditto OpenMCL). Rather, this behavior must be hard coded 
into their readers.

regards,

Ralph




Raffael Cavallaro, Ph.D.
raf...@ma...