Containment
jankapunkt opened this issue · 6 comments
There needs to be a boolean operation on instances of Sets that allow the following:
What you say: "if A is a proper superset of B, ..."
What you type: if (A.isProperSuperset(B)) {
note: After some nail biting, I settled on the word 'of' being builtin to functions. We say "f of x" and we write "f(x)". We don't write the of, but instead it is as-if the open-parenthesis is the of.
What you say: "if A is a proper subset of B, ..."
What you type: if (A.isProperSubset(B)) {
branch: matt/containment
jankapunkt said:
Looks fine. I assumed that there is no reason to implement this on the Set class level (i.e. for arbitrary args) as I saw no use-case for that. Can you confirm this?
This PR would be part of the 2.x.x release.
matt (i) said:
The only use case I could think of is if people want to verify that a list of sets is a chain of subsets.
If < denotes "subset", then a person wanting to check if
A < B < C < D
could do something like
Set.isSubset(A, B, C, D)
. I don't know how often somebody would want to do this, but it is convenient. It's up to you.
If it is not a big deal to add (introducing more complexity than already exists) and you think it could be a use case then let's add it. With this package completeness and validity is more interesting than performance.
This is typically called "a chain of subsets". As a random example, see (http://www.mathcounterexamples.net/uncountable-chain-of-subsets-of-the-natural-numbers/)
I don't know if we would want to call it isChainOfSubsets to be unambiguous.
What do you think?
I'm really on the fence. We might leave this for after version 2 release.
Can this be closed as it is now already merged into 2.x.x?
Yeah. We can leave isChainOfSubsets stuff for another time.