To: William Chesters <email@example.com>
Subject: Re: Proposal for study: Add a categorical Initial type to ocaml
Date: Sun, 10 Oct 1999 18:36:30 -0400
I read the referenced note
and while I agree with most of what's said there, I think that putting
the "option" attribute onto a field would reduce its value.
Specifically, it is a highly common (albeit problematic) idiom in C,
C++, Java, and other languages, to program with a pointer to X, which
is perhaps null, and is only checked late, at the point when it is
That sort of idiom would not be possible to capture -- when we fetch
the value of an "option" field, we are implicitly asking for the field
to be checked for non-null-ness.
In other words, I think that "nullability" is a useful property of
types in general, and not merely of types of fields.
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