(j3.2006) Liaison to IFIP WG 2.5

Bill Long longb
Tue Aug 21 15:32:34 EDT 2007

Lawrie Schonfelder wrote:
> I think for once I am sort of agreeing with Bill, Mike and Alex, only sort of!

[generally insightful comments on intervals deleted]

> I would have to say that co-arrays are also not generally applicable. As an optional part/TR they
> are obviously desirable but since they are clearly an architecturally specific efficiency aid, not
> providing general problem solving expression support,  I remain emphatically opposed to their
> inclusion as a core part of Fortran in much the same way as I would not wish intervals to be
> included as an intrinsic.
Here I do not agree.  Co-arrays are aimed at parallel computing, and in 
Fortran's niche in the market place that is the typical application.  
Co-arrays provide the expression support for that task.  Unlike the 
situation for intervals, the relevant hardware (multi-core systems) 
already exists, and in the 2010 time frame will be essentially 
universal. Sure, there will be a few people still writing serial Fortran 
code in 2010.  For them, having co-arrays in the standard is a 
non-issue.  If you don't use them, the code you end up writing is as if 
they were not in the standard at all.  But for the mainstream user base, 
having co-arrays in the core language is essential to code portability 
as it sets the standard for implementations.  Ultimately, code 
portability is the primary purpose of language standardization.  We need 
to stay focused on that goal, and accept and embrace the present and 


Bill Long                                   longb at cray.com
Fortran Technical Support    &              voice: 651-605-9024
Bioinformatics Software Development         fax:   651-605-9142
Cray Inc., 1340 Mendota Heights Rd., Mendota Heights, MN, 55120


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