[slime-devel] Re: defining LISP functions in Emacs

[Tobias C. Rittweiler]

Joe Corneli <jcorneli at planetmath.org> wrote on 2007-06-20:

> I am trying to continue on the quest I described before --
>
>  "I want to create a variant of `defun' that takes arguments from
>  Emacs and assembles a body to be evaluated by SLIME."
>
> ...
>
> Here is a macro that accomplishes this:
>
> (defmacro lefun (name arglist &rest body)
>   `(defun ,name ,arglist 
>      (slime-eval (list (append (list 'lambda ',arglist) ',body) , at arglist))))
>
> Unfortunately, it still produces an error when I test it with the
> following code:
>
> (lefun myplus (a b) (+ a b))
> (myplus 2 3)
>
> Specifically, the above triggers SLDB with the following message:
>
> Execution of a form compiled with errors.
> Form:
>   ((LAMBDA (A B) (+ A B)) 2 3)
> Compile-time error:
>   illegal function call
>
> I do not know what this means.

Forms comming from Emacs to SWANK (the Common Lisp side of Slime) are
READ in the :SWANK-IO-PACKAGE, i.e. the form that was really evaluted in
Common Lisp looked liked this:

  ((SWANK-IO-PACKAGE::LAMBDA (A B) (SWANK-IO-PACKAGE::+ A B)) 2 3)

Which is not a valid form according to CL's evaluation model.

You have to send symbols to CL with an explicit package identifier:

  (defmacro lefun (name arglist &rest body)
    `(defun ,name ,arglist 
       (slime-eval (list (append (list 'cl:lambda ',arglist) ',body)
                         , at arglist)))) 

and

  (lefun myplus (a b) (cl:+ a b))

HTH,

  -T.