multithreading - TMVar, but without the buffer? -


i'm trying communication between haskell lightweight threads. threads want send each other messages communication , synchronisation.

i using tmvar this, i've realised semantics wrong: tmvar store 1 message in internally, positing message empty tmvar won't block. it'll block if post message full tmvar.

can suggest similar stm ipc construct which:

  • will cause writes block until message consumed;
  • will cause reads block until message provided?

i.e. zero-length pipe ideal; don't think boundedchan happy if gave capacity of 0. (also, it's not stm.)

if understand problem correctly, don't think can, since transactional guarantees mean transaction can't read transaction b's write until transaction b committed, @ point can no longer block.

tmvar closest you're going if you're using stm. io, may able build structure completes write when reader available (this structure may exist, i'm not aware of it).


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