Subject: Re: How can I obtain type errors
From: Erik Naggum <>
Date: 1999/06/02
Newsgroups: comp.lang.lisp.franz,comp.lang.lisp
Message-ID: <>

* Antonio Garrido Tejero <>
| I'm using Allegro Common Lisp and I want to define a function with
| arguments of a specific type.


| For example, the typical function:
| (defun df* (a b)
|      (declare (double-float a b))
|      (* a b))
| should fail with (df* 2 3), but it works!

  great, isn't it?

| How can I get a type error?

  you can do

(defun fd* (a b)
  (check-type a double-float)
  (check-type a double-float)
  (* a b))

  if you think you are going to win a speed contest with your type
  "checking", you aren't.  is that why you want this stuff?

@1999-07-22T00:37:33Z -- pi billion seconds since the turn of the century