Thank you for your assistance.
It looks like you are correct. However, while the compiler may be
smart, it's not smart enough to see that there's a secondary guard
variable that prevents any access of the list-length result if the
argument is nil. The same goes for the when evaluation.
== Steven
On Sep 23, 2008, at 2:12 AM, Madhu wrote:
[pardon the top post, if you find it inappropriate]
The CLHS entry for LIST-LENGTH says:
,----
| Returns the length of list if list is a proper list. Returns nil if
| list is a circular list.
`----
This means one of the possible return values is NIL. The compiler
diagnostics seem to indicate that it has inferred that the value
returned by LIST-LENGTH are used only in number contexts.
The compiler is warning you that there will be an error in the event
LIST-LENGTH returns NIL.
I suspect the case with the other diagnostic is similar. It is likely
you are using the return value of a (WHEN clause) where the compiler
always expects a number.
Both of these deal with the specifics of your code , so it is likely
the compiler knows better (as it has access to the code) than us (who
dont:)
