Subject: Re: Numbers in Lisp (was: macros vs HOFs)
From: Erik Naggum <>
Date: 17 Sep 2002 13:53:24 +0000
Newsgroups: comp.lang.lisp
Message-ID: <>

* Alexander Schmolck <>
| How does knowing that 'a' is of type rational completely determine the return
| type of (sqrt a)?

  Please try to understand.  The argument to `sqrt´ is of type `number´, and
  the return value is of type `number´.

| What makes you think I disagree with this?

  Your repetitive argument about division.

| I'm not.

  Sometimes, other people are better judges of such things than oneself.

| I'm simply interested in the practical experiences [...]

  But you cannot do that usefully without understanding the theory.

| I still think trying to draw from the practical expertise of other people is
| often vastly superior to trying to derive something from first principles or
| just adopting what is most common.

  Sure, but you need to understand fully what they have practical expertise in.

| It is of course possible that what I want to know about is really to
| imprecise or otherwise unsuitable to be properly answered in that way.

  It has appeared to me that you lack foundation in your quest for knowledge
  and thus that there is a high risk of leading you astray given truth that
  you will misinterpret.

| If you mean of the first: (expt 27 1/3), (log 8 2) etc.

  I meant specifically the compatibility problems you alluded to.

Erik Naggum, Oslo, Norway

Act from reason, and failure makes you rethink and study harder.
Act from faith, and failure makes you blame someone and push harder.