Identities do not mess anything up, the commonly employed implementations of identity however do... again check out modula-3 and more recently the paper at htt

Identities do not mess anything up, the commonly employed implementations of identity however do... again check out modula-3 and more recently the paper at http://drops.dagstuhl.de/opus/volltexte/2015/5231/ http://drops.dagstuhl.de/opus/volltexte/2015/5231/ Apologies I meant the identity of the hash algorithm e.g. MD5, attached to the bits produced by running the hash algorithm on an object, while hash collisions are absolutely accepted, mixing hash values produced by different hash functions is generally frowned upon. Identity at the structural level is very much either you care about the identity, or you do not (in which case "this one"...), maybe 99.9% of the time "this one" suffices, however the takeaway from this should be that identity of structurally transparent objects should be ignorable, rather than structurally transparent objects should not have identity should one care to acknowledge it.