Re: Can LPeg do basic arithmetic?

[Sean Conner <sean@...>]

It was thus said that the Great Soni L. once stated:
> On 05/07/16 09:37 PM, Sean Conner wrote:
> >It was thus said that the Great Soni L. once stated:
> >>The goal is to never run Lua code for it. 

  So we're back to the above:

	  lpeg.P"0+0" * lpeg.Cc(0)
	+ lpeg.P"0+1" * lpeg.Cc(1)
	...

although if you want to deal with whitespace:

	plus = lpeg.S" \t\v\r\n"^0
	math = lpeg.P"0" * plus * lpeg.P"0" * lpeg.Cc(0)
	     + lpeg.P"1" * plus * lpeg.P"1" * lpeg.Cc(1)
	     ...

  That's the best (enumerate all possible inputs) short of unary
non-negative "numbers".  And if you are going *that* route---the ultimate
golfed fizz-buzz:

	https://codon.com/programming-with-nothing

(and even then, he cheats by avoiding actual I/O)

> >>Perl regex can run Perl code,
> >>but the linked math-with-regex thingy doesn't use that and that's the
> >>whole point. If someone ports LPeg to a different programming language,
> >>a LPeg that calls Lua code will stop working.
> > 
> >   That was never specified as a limititation in your initial post.
> 
> No, but it is mentioned in the linked stackoverflow question. You should 
> read the full context before replying.

  Touche'

> >>Also, if this was a codegolf or programming puzzle and you weren't
> >>allowed to use the language's built-in addition subtraction etc, you
> >>could do it with regex instead.

> >   If this was a codegolf or programming puzzle and you weren't allowed to
> >use the languages's built-in addition subtraction etc, you wouldn't be
> >*ABLE* to do this using LPeg.  Period.  End of story.  That '*' in the 
> >above example?  That's Lua multiplication operator.
>
> You're mistaking "operation" and "operator". In other languages, "+" is 
> often overloaded for concatenation as well as addition, and in such 
> challenges you're (usually) still allowed to use "+" for concatenation. 

  Then what would you call the '*' operator?  Leslie?

  -spc