[swift-corelibs-dev] Why isn't Foundation shipped in OS X and iOS open source?

Kiel Gillard kiel.gillard at gmail.com
Wed Apr 13 19:32:04 CDT 2016

Hello all,

I’m considering contributing yet part of me feels hesitant or reluctant to do so because I do not want to do a poor job at what feels like I’d be reverse-engineering the Foundation APIs (as opposed to Core Foundation and the pure Swift Foundation).

Perhaps I missed the answer somewhere else or maybe I’m lacking the imagination to come up with reasons myself, but why isn’t Foundation (as it ships in iOS and OS X now) open source, too?

Wouldn’t a pure Swift implementation of Foundation benefit from insights from the implementation details of Foundation? For example, Foundation may have implemented such-and-such an API in a particular way for performance reasons that would be unacceptable if released. That insight may be lost by providing a Swift implementation of an API that merely reproduces the same output from the same input. Concretely speaking, I seem to recall such a conversation a few months ago or so with respect to the implementation NSJSONSerialization (unfortunately, I can’t seem to find the thread).

I’m not suggesting a pure Swift Foundation should be a one-to-one port of Foundation’s implementation, but surely it would be helpful (not just for me, but for others too) to take the learnings of a mature API into account when implementing Swift Foundation?



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