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Date:         Mon, 9 Jun 2014 14:25:07 +0200
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From: =?ISO-8859-1?Q?Lars_Hellstr=F6m?= <Lars.Hellstrom@RESIDENSET.NET>
Subject: Re: Juxtaposition in l3fp
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Status: R

aparsloe skrev 2014-06-08 11.53:
> Should l3fp use juxtaposition *at all* to indicate multiplication? I am=
 an
> enthusiast for l3fp. I am using it constantly (in LyX using LyX's insta=
nt
> preview to evaluate formulas), but that has simply heightened my unease
> about using juxtaposition to indicate multiplication, particularly as p=
art
> of a kernel package.

Syntactic sugar: may look like yum, but it can hurt you. :-)

> Most people using numbers have their mental reflexes shaped either by
> mathematical usage or calculator or spreadsheet usage. The last two, to=
 my
> knowledge, don't allow juxtaposition. Multiplication must be explicitly
> indicated with an asterisk.

You conspicuously omit programming languages, which I would put as a=20
forerunner of spreadsheets (the less about said, the better), and probabl=
y=20
also of modern calculators that attempt to display formulae. So it probab=
ly=20
all boils down to "because that's how it was in FORTRAN" (which, if memor=
y=20
serves, ignored spaces).

A data point of possible interest is MetaFont, which has some cases of=20
juxtaposition as a high priority operation (e.g. 2/3x means two thirds of=
=20
x). Since it's Knuth, it's probably very consistent, but not necessarily=20
intuitive.

> Mathematical usage is variable and often irregular

Oh yes. One of the really big mistakes people make when trying to impleme=
nt=20
mathematics is believing that the mathematical formula language is=20
consistent, just because it is precise. Juxtaposition can denote pretty m=
uch=20
*anything* (depending on context), and because juxtaposition is=20
multiplication, it follows that pretty much anything can be regarded as a=
=20
kind of multiplication. ;-)

Lars Hellstr=F6m