[thesz]

SPJ of Haskell fame once discussed perceived STM failure in .Net: https://haskell-cafe.haskell.narkive.com/t6LSdcoE/is-there-a...

Basically, poor STM performance in .Net is too much mutation and mutation-induced logging. This is why clojure's STM is much more widely used.

I have particularly deep experience in various Haskell projects and I must insist that no relatively (1) big Haskell project (2) with a hint of concurrency and (3) developed by several people can go without use of STM.

I can use MVars myself for problem space discovery. When there are at least two of use, I will use TVar and insist others should too.