topics: add equality

[robphoenix]

I noticed the topic Structural equality in the F# track here.

Is it worth adding an equality topic to the TOPICS.txt list? This is derived mostly from the Clock exercise.

Not necessarily Structural equality, maybe Relational equality, Equality comparison, Equality testing or just Equality ??

Honestly, I don't have the experience to make a judgement on this, especially with regards to different interpretations of equality by different languages.

[rpottsoh]

@bordeltabernacle how about something along the lines of Operations? ie. =, +, - , / , *, etc. or Relational Operations, <, >, <=, >=, =?

[robphoenix]

I'm not sure, I was considering less some kind of mathematical operation and more the assessment of one thing being the same as another. For instance in the clock exercise we're told that Two clocks that represent the same time should be equal to each other. The term structural equality seems to fit better here than the concept of an operation. I realise this can mean different things in different languages, and I guess it's that idea of how is one type or object equal or different to another?

[Insti]

Just Equality seems reasonable for a topic.

[rpottsoh]

OK. How about both Equality and Operations? Generally speaking Operations seems to be missing to me.

[Insti]

Are there any problems that don't use operations?

[rpottsoh]

@Insti 😄 I doubt it. I only mention it here as a matter of course. How consice should topics.txt be, or what is the purpose of topics.txt?

[Insti]

In order to categorise exercises for future searching, tracks can add the topic(s) of exercises to their config.json file. In order to maintain some cross-track consistency the topics.txt list acts as an overall master list that tracks can refer to. (There is currently no enforcement of this.)

There's a big discussion about it here: exercism/discussions#60

[rpottsoh]

@Insti thanks for pointing me to that issue. With the entirety of that issue fresh in my mind Equality, as you suggest, would be a good addition to consider.

[robphoenix]

Thanks @Insti I'll open a PR to add Equality. Also interesting to note that topics.txt is not an enforced list for languages to adhere to. I did wonder that seeing the F# config.json