GNUStep is a good example that the bare bones language and compiler being open source it is not enough, when everything else doesn't come along.
Saying this as someone that used Afterstep and Windowmaker alongside GNUStep, and did seat a few times on the GNUStep room at FOSDEM.
Last time I checked was at the level of OS X Panther, and modern Objective-C still wasn't supported.
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