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A comment on Functional programming in C++ (2012). Parent comment

Re:Functional programming in C++ (2012) by jcelerier on Tuesday December 29, 2020 @04:56AM (#25568326)
> But in computer science there is another common definition which involves side effects not being repeated (that is, `f(); f();` is the same as `f();`).

where have you ever seen that definition ?!

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Re:Functional programming in C++ (2012) by halter73 on Tuesday December 29, 2020 @05:06AM (#25568380)
> in imperative programming, a subroutine with side effects is idempotent if the system state remains the same after one or several calls

https://en.wikipedia.org/wiki/Idempotence#Computer_science_m...

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Re:Functional programming in C++ (2012) by thewakalix on Tuesday December 29, 2020 @06:02AM (#25568666)
It’s used commonly when working with unreliable communication (e.g. networking). For example, if you make a request but you don’t get a response, either the request or the response might have failed to send. It’s convenient if you don’t need to determine which case occurred; idempotent functions free you from worrying about whether the requested action was carried out.
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