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Re: .kv ?
From: Brandon Allbery
September 14, 2018 22:11
Re: .kv ?
Message ID: CAKFCL4UOCXHiztZMyqqJXGpihWq1Lq+F_d7qCu=3-dQmfNHyJw@mail.gmail.com
On Fri, Sep 14, 2018 at 5:56 PM ToddAndMargo <ToddAndMargo@zoho.com> wrote:
> 'To opt into a non-nullable version of a type add the :D
> "smiley" to it."
> This is confusing. And I don't think correct, but I could be wrong.
> Curt stated it a lot better:
> If I say "my Int $x",
> $x is now an Int, but an undefined Int.
> If I say "my Int $x = 42",
> $x is an Int, but set to a defined value, 42.
> ":D" means that the variable is "defined". "non-nullable" is
> a confusing way to state it.
Not exactly. "Defined" is a "now" thing; "non-nullable", via type smileys,
is an "always" thing. It is defined now, and it can never be undefined.
> To me ":D" means that the variable has something assigned to
> and ":U" means that the variable has yet to have anything
> assigned to it.
> If I were to rewrite this, I'd reverse D and U as that
> is the way they evolve. All variables start out as :U.
This is the same misunderstanding: what is now, is not guaranteed to be so
in the future. :U and :D provide such guarantees. Merely being defined or
undefined right now says nothing about the future.
brandon s allbery kf8nh