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Re: Bug with transpose in functions
From: |
Wols Lists |
Subject: |
Re: Bug with transpose in functions |
Date: |
Fri, 12 Jul 2019 20:09:52 +0100 |
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Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.7.0 |
On 12/07/19 19:04, Werner LEMBERG wrote:
>
>> Functions like transpose act destructively on their argument, so you
>> need a copy or the original will get changed. [...]
>
> How can Joe User find out whether a function is acting destructively?
>
Computer pedant here :-)
Functions do not have side effects, and for any given input they always
return the same output. So if this is a PROPER function, it cannot act
destructively :-)
Obviously it isn't, so it's technically a subroutine that returns a
value. Dunno how you tell the difference, but that's why you get
computer languages where all variables are "write once" - everything is
based on proper functions.
Maybe the documentation should make a point of saying whether functions
are "proper" or "improper". :-)
Cheers,
Wol