OpenEuphoria

Re: Strings and the like.

• Posted by Irv Mullins <irv at ELLIJAY.COM> Dec 09, 1999
• 514 views

On Thu, 09 Dec 1999, Everett Willaims wrote:

> At last some meat and potatoes. I NOW see the equal function. Somehow,
> I had missed it previously. I still don't see the need for it. The highest
> level
> comparison is the natural one, all others should be handled either implicitly
> or by function where functions return values. In the syllogism, logic is
> binary. The equal sign means equivalence. It does not deal with values.
> It deals with the path to be followed. It is a switch set by the values on
> either side of it. There is no problem when a function returns multiple
> values in a sequence. That is consistency. The equal sign as assignment
> operator deals with values. It creates no inconsistency when it allows
> multiple values to be assigned. When multiple values are returned by
> an equivalence that "can" have and demands a single value, consistency is
> not served. It is not difficult for the interpreter to distinguish situations
> where a single value is required. There is no inconsistency or programmatic
> problem when comparing any two values or sets of values in a structure as
> long as both the structure and the values are equivalent. But, they are
> either equal or unequal, true or false, then or else.

Now this is an actual problem, which is a source of confusion in the beginning,
and a continuing aggravation thereafter.

Why, indeed, shouldn't the = within an 'if a = b then...' construct return a
true/false result, computed as follows:
 1. if the lengths are different, return false
 2. if every byte of a = every byte of b,  then return true
     else return false

In part, this would help achieve a kind of symmetry within the language:
a = 5
if a = 5 then....

b = "Bill"
if b = "Joe" then.... nope, no need for an error, Bill will never equal Joe
if b = 5 then....       ditto.

For the rarer case when we actually need a byte-by-byte comparison returned -
(somebody suggest an appropriate keyword)
a = "Bart"
b = "Bill"
? coincidence(a,b)
returns: {1,0,0,0}

Regards,
Irv