From: Yukihiro Matsumoto <matz@...>
Date: 2009-10-04T22:39:05+09:00
Subject: [ruby-core:25933] Re: [Bug #2114] Array Hash inconsistency

Hi,

In message "Re: [ruby-core:25835] [Bug #2114] Array Hash inconsistency"
    on Tue, 29 Sep 2009 17:29:47 +0900, Wim Yedema <redmine@ruby-lang.org> writes:

|I believe the essence of a Hash table is the mapping from key to value. This mapping is a surjective function a key maps to one value but multiple keys can map to the same value. This essence does not seem to be represented by modelling the Hash as a collection of key-value pairs. It allows the a key to occur multiple times and to map to different values. This essence is also present in Arrays, but in a more specialized form where keys are integers. For me this is the reason to prefer this view.

Seeing Hash as collection of key-value pair does not directly mean
allowing keys to appear multiple times.  For example, Set is a
collection of values, but the value should be unique.

|Be that as it may, it's not worth it to break a lot of existing code over this. It might be nice to provide an alternate interface to the Hash implementation, such that a programmer can choose his favorite view.

Proposal for API is welcome.

							matz.