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Date: Sun, 25 Apr 2021 09:04:06 +0200
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To: Larry Garfield <larry@garfieldtech.com>
Cc: php internals <internals@lists.php.net>
Content-Type: text/plain; charset="UTF-8"
Subject: Re: [PHP-DEV] [RFC][Draft] Sealed Classes
From: olleharstedt@gmail.com (=?UTF-8?Q?Olle_H=C3=A4rstedt?=)

> A total function is a function that is defined over the entire domain of its
> inputs.  For example, addition is a total function over integers, because
> for every possible pair of integers you pass to it there is a logical return
> value.  However, square root is not a total function over integers because
> there are some integers you pass it for which there is not representable
> return value.  (Negative numbers, unless you get into imaginary numbers
> which PHP doesn't support.)  In those cases, you have to throw an exception
> or return an error code or similar.

Maybe nitpicking, but PHP-land shouldn't make up their own
definitions: "A total function is a function that is defined for all
possible values of its input. That is, it terminates and returns a
value." https://softwareengineering.stackexchange.com/questions/334874/in-the-context-of-functional-programming-what-are-total-functions-and-partia

Which means a total function is guaranteed to not have any errors,
like exceptions or division by zero. Compare with languages F* or Koka
which support this notation.

I get your point tho. :)

Olle