OpenEuphoria

Re: A bug in the interpreter

• Posted by Ed Davis <ed_davis2 at yahoo.com> Feb 28, 2006
• 452 views

Daryl Border

>   It is not the responsibility of the interpreter to prevent
>the programmer from using poorly formed expressions such as (4 <
>n) < 8.

Some people might say that "4 < n < 8" is a poorly formed
expression.  If you are coming from the C/Java world, you would
say it is perfectly valid, but it does not mean "4 < n and n <
8", but rather the (4 < n) < 8.

>It is the responsibility of the interpreter to evaluate the
>expressions according to the rules of mathmatics. My code
>evaluates both expressions correctly. Euphoria currently does
>not.

How does it correctly evaluate (4 < n) < 8?  Does it treat (4 <
n) as a boolean, and then compare against that?

What about "4 < n < 8 < a < b"?  How should that be evaluated? Is
it "4 < n and n < 8 and 8 < a and a < b?"  Should the interpreter
allow that? How do your changes evaluate it?

Along the same lines, what about:  "4 = n = 8"?  It is also
currently accepted, and apparently interpreted as:

(4 = n) = 8

The same way C would interpret it (well, replace the '=' with
'==').

Without understanding all the possible ramifications, I'm not
sure changing the current semantics is a good idea.