destructuring-bind
vlad-km opened this issue · comments
JSCL
CL-USER> (destructuring-bind (name . bind) (cons :name 2)
... (values name bind))
...
ERROR: CDR called on non-list argument
CL-USER> SBCL
CL-USER> (destructuring-bind (name . bind) (cons :name 1)
(values name bind))
:NAME
1
CL-USER> Obviously, the problem is not hot, if no one has encountered it.
Good catch.
Obviously, the problem is not hot, if no one has encountered it.
I think it is quite important! and you did find it :-)
I guess we didn't notice that because I tend not to use (a . b) while restructuring, but &rest instead.
Conveniently, the lambda-list.lisp implementation works fine on other implementations too. So if you try the same example in the (jscl) destructuring-bind running on SBCL, we get more information:
JSCL> (!destructuring-bind (name . bind) (cons :name 2)
(values name bind))
gives:
The value
2
is not of type
LIST
[Condition of type TYPE-ERROR]
...
Backtrace:
0: (VALIDATE-REQVARS (:NAME . 2) 1)
The stacktrace can be useful to fix it.
The first error it encounters is that we use validate-reqvars to validate the minimum length of the list, which uses length, but it fails with improper lists.
I suspect there is also an error while parsing the lambda-list, because of this example:
JSCL> (lambda-list-restvar (parse-destructuring-lambda-list '(bind . name )))
(NAME)
JSCL> (lambda-list-restvar (parse-destructuring-lambda-list '(bind &rest name)))
NAME
It is a nice issue. @vlad-km , if you or someone else wants to give it a try. Otherwise I'll have a look in a few days
I plan to release a system update in a couple of weeks - types, condition and structure.
I will make an announcement of updates in the coming days.
This error will wait. I use &rest too.