Pointer comparisons to nil

[chris hermansen]

Good evening all;

I have a question that stems from a subject line to a recent post of Jose's:

more mode equivalencing to accompany pointer comparison in a68-moids-misc.cc


One of the things that has "got me" on several occasions is writing a
comparison like

*if* some pointer *is* *nil* *then* ... *fi*

which of course¹ fails because nil is not of the same mode as
some_pointer.  Now I don't mind that I can't compare pointers to nil, but I
would really like it if Algol 68 would stop me from doing that; or at least
warn me.

Does anyone have an opinion on this?  Will GNU Algol 68 have an opinion on
this?

Thanks in advance!

[1] I think I ran into the back in the day working with Algol68s, but that
was long ago and far away.  More recently, I thought at first it was
something to do with Algol 68 Genie but I'm quite positive I spotted the
need to cast nil to the mode of some pointer in McGettrick's textbook from
the 1970.

-- 
Chris Hermansen · clhermansen "at" gmail "dot" com

C'est ma façon de parler.
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