OpenEuphoria

Re: match() (not short, he he)

• Posted by gertie at visionsix.com May 26, 2003
• 341 views

On 26 May 2003, at 15:56, jbrown1050 at hotpop.com wrote:

> 
> 
> On Mon, May 26, 2003 at 02:41:47PM -0500, gertie at visionsix.com wrote:
> > 
> > 
> > On 26 May 2003, at 15:04, jbrown1050 at hotpop.com wrote:
> > 
> <snip>
> > > what would match({"at"}, {"k","","at"}) return?
> > 
> > 0
> 
> That is wrong. If match("at", "kat") returns 2, then 
> match({"at"}, {"k","","at"}) should return 3. 

but match("at",{"k","at"}) would return 2, right?
so why would nesting the "at" even deeper match({"at"},{"k","at"}) also return 
2?

> What you appear to be proposing is
> turning match() into find().

It has often confused me that there are 2 functions that do almost the same 
thing: match() and find().
 
> <snip>
> > > To avoid retyping, i'll add these constants:
> > > 
> > > constant x = {"k","","at"}, y = ""
> > > 
> > > y is an element of x, but it is not a subsequence of it. I think, that
> > > using
> > > match() to find elements (even if the element itself is a sequence) is a
> > > bad
> > > idea (but not so bad that it should be a run-time error).
> > > 
> > > I think, we should be universal ... if match(y, x) returns 2, then
> > > match('a', "kat") should also return 2.
> > 
> > Correct! Now you've got it!
> 
> And I think that being universal in allowing atoms is incorrect. That makes
> certain sequence matching extremely complex, to the point of confusion.

But in "kat", each character is an atom. In {"kat"}, "kat" is a sequence inside 
another sequence { }. For the 'k' to be a sequence, it should read as 
{"k","a","t"}. In {'k',"at"}, 'k' is an atom, and "at" is a sequence. Unless you
specify 'k' is a sequence, as in {"k","at"}. In {"k","at"}, 'k' is not found
except
as the first element of the first subsequence. So if i specify 
match('k',{"k","at"}), 0 should be returned. In match("k",{"k","at"}), 1 should 
be returned. And if that is true, then un-nesting the "k" and "at" from their 
own subsequences, to form match('k',"kat"), should return 1, since "kat" 
should equal {'k','a','t'}.

Kat