I had a little debate going on with a coworker. Simply put, is there a good reason to hide/encapsulate functions that are pure?By pure I mean the wikipedia definition:Always returns the same results from the same input. (For the sake of this discussion Foo Create(){ return new Foo(); } is considered impure if Foo does not have value semantics.)Does not use mutable state (except local variables) or I/O.Does not produce side effects.
Is there a good reason to make pure functions non-public?
design;pure function
A pure function could still be an implementation detail. Although the function may cause no harm (from the point of view of not breaking important invariants/contracts), by exposing it both the author and the users of that class/module/package lose. The author loses because now he can't remove it even if the implementation changes and the function is no longer useful to him. The users lose because they have to sift through and ignore extra functions that aren't relevant to using the API in order to understand it.