On 12 July 2013 22:46, Serhiy Storchaka <storchaka@gmail.com> wrote:
13.07.13 00:27, Joshua Landau написав(ла):
On 12 July 2013 18:58, Serhiy Storchaka <storchaka@gmail.com
<mailto:storchaka@gmail.com>> wrote:
    I agree. But how is it related to ½ and 3.(142857)?
½ === 1/2; thus is an expression

0.5 === 5/10. Isn't it an expression?

No. That's like saying "1 === 2/2". There is a much more obvious equivalence between two ways of writing "1/2" than between two ways of displaying the result of "1/2".
 
3.(142857) is more ambiguous, because there's not actually any
mathematical operator in place. But it is too much parsing for no
benefit, AFAICT; you would complicate something simple to solve almost
no use-cases, and then when they are used it's harder for people to work
out what is meant.

AFAIK children teach 3.(142857) before ∞. I'm sure people use fractions and recurring decimals more often than infinity.

In my experience (I'll take a good wager I'm younger than you) people learn first about infinity, then are taught recurrence using the floating-dot syntax. The bracket form for recurrence was not taught once during high-school for me, and although "infinity" was hardly covered either it's not niche knowledge.

Plus, why on earth would you use recurrence for floats? Give me a use case. There's a good reason for float infinity.

Note that I'm British.
 
The informal definition for "expression" with regards
to int and float I'm using is basically the measure of how much more
parsing code would need to be implemented.

½ requires no more parsing code then ∞.

Au contraire, if you accept ½ you are bound by law to accept all of the other fractions -- that's much more code than just allowing ∞.