concurrency.md

@@ -78,6 +78,14 @@ initial proposal is here:
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+Alternate, simpler proposal: full memory barrier at every putMVar and takeMVar.
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+perhaps a better phrasing of the first proposal exists, in practice, from a users point of view, it would be hard to tell the difference between the two models, but we should say something concrete on the matter.
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 ## Misc library stuff