OpenEuphoria

Re: Error in Euphoria compiler?

• Posted by Robert Craig <rds at RapidEuphoria.com> Jun 06, 2004
• 541 views

David wrote:
> I noticed a discrepancy between how the interpreter and compiler treat 
> sequences in tests. For example:
> 
> <font color="#330033"></font>
> <font color="#0000FF">if </font><font color="#00A033">"this is a sequence"
> </font><font color="#0000FF">then</font>
> <font color="#FF00FF">   puts</font><font color="#330033">( 1, </font><font
> color="#00A033">"it's true" </font><font color="#330033">)</font>
> <font color="#0000FF">else</font>
> <font color="#FF00FF">   puts</font><font color="#330033">( 1, </font><font
> color="#00A033">"it's false" </font><font color="#330033">)</font>
> <font color="#0000FF">end if</font>
> <font color="#330033"></font>
> 
> Running under the interpreter, it throws a bad type error. The compiler 
> figures out that it's not an integer or atom, but instead of throwing a type 
> error, it just evaluates it as false.

The compiler's (i.e. translator's) mandate is to make your
program run fast. It catches all compile-time errors but is not 
required to catch run-time errors (subscripts out of bounds,
incorrect type of data etc.).
It does catch a few run-time errors, mostly in run-time routines 
shared with the interpreter, but by and large it assumes that you 
have debugged your program already using the interpreter.

Using a sequence in an if-condition is handled as a run-time
error, although in your example it's pretty obvious at 
compile-time. I could add a bunch of semi-redundant ad-hoc 
tests for specific errors like this in the shared front-end, 
but I'm not keen to do so, unless there's something that 
comes up with great frequency.

Regards,
   Rob Craig
   Rapid Deployment Software
   http://www.RapidEuphoria.com