[J3] [EXTERNAL] [BULK] GNU Ada Translator GNAT has physical units checking

[Clune, Thomas L. (GSFC-6101)]

Hi Van,

Templates should enable much (probably not all) of what you might want in terms of checking physical units.    See this paper that Magne presented at the Tokyo meeting:

https://j3-fortran.org/doc/year/19/19-188.pdf


  *   Tom
  *

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Thomas Clune
Lead, Software Infrastructure
Global Modeling and Assimilation Office
NASA Goddard Space Flight Center
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Thomas.L.Clune at nasa.gov<mailto:Thomas.L.Clune at nasa.gov>


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Date: Tuesday, July 29, 2025 at 6:08 PM
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Subject: [EXTERNAL] [BULK] [J3] GNU Ada Translator GNAT has physical units checking
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The GNU Ada Translator GNAT has physical units checking. See

https://gcc.gnu.org/onlinedocs/gnat_ugn/Performing-Dimensionality-Analysis-in-GNAT.html

It's not as complete as what I proposed, which was temporarily on the 2008 Fortran work plan.

I originally proposed in 1976 during the requirements gathering process for what was then called DOD/1 that it ought to include units declaration and checking. Colonel Whittaker wondered why a language explicitly designed for reliability would have a use for it.

I sent my most recent refinement, cast as a TS, to Tucker Taft, the head of the US delegation to the SC22/WG9 Ada committee. He said they are considering whether they want to extend the GNAT system and maybe standardize it.

Does Fortran want to reconsider a system of physical units declaration and checking, even if only as a TS that might never be standardized, or is the topic permanently off the table?

--- Van Snyder

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