On 09/06/2014 13:25, Lars Hellström wrote: > 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 instant >> preview to evaluate formulas), but that has simply heightened my unease >> about using juxtaposition to indicate multiplication, particularly as >> part >> 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 > forerunner of spreadsheets (the less about said, the better), and > probably also of modern calculators that attempt to display formulae. So > it probably all boils down to "because that's how it was in FORTRAN" > (which, if memory serves, ignored spaces). > > A data point of possible interest is MetaFont, which has some cases of > juxtaposition as a high priority operation (e.g. 2/3x means two thirds > of x). Since it's Knuth, it's probably very consistent, but not > necessarily intuitive. > >> Mathematical usage is variable and often irregular > > Oh yes. One of the really big mistakes people make when trying to > implement mathematics is believing that the mathematical formula > language is consistent, just because it is precise. Juxtaposition can > denote pretty much *anything* (depending on context), and because > juxtaposition is multiplication, it follows that pretty much anything > can be regarded as a kind of multiplication. ;-) > > Lars Hellström I guess Bruno can say more, but I suspect that requiring explicit "*" for multiplication might have a benefit in terms of code complexity (no need to allow for other cases). An obvious question for me is would such a position lead to problematic cases? The comparison with MetaFont is probably a useful one in this regard. -- Joseph Wright