What is the reason for `Map<K, V>.filterValu...

# stdlib

[gregorbg]

What is the reason for Map<K, V>.filterValues working directly on the values (i.e. it expects (V) -> T) as opposed to Map<K, V>.mapValues working on the entire entry (i.e. it expects (Map.Entry<K, V>) -> T)? Same question applies to the signature of filterKeys vs. mapKeys and similar functions.

[voddan]

Isn't it what Map.filter is working on?

[spand]

An observation is it is the only difference with filterValues and filterKeys, filter is the parameter. I assume the reason you have different methods with map is to avoid returning pairs where the one component is always the same.

[spand]

So for filter it is about specializing on the input paramter wheres with map it is specializing on the return value kind

[Dico]

The reason is simply convenience. There is Map.filter for filtering the entries as @voddan pointed out.