Well, bracket doesn't work with concurrent programs even in the absense of signals (except in the main thread) so you don't lose anything there. If you write a concurrent program and want its threads to clean up, you always have to code that yourself, for example using a bracket in the main thread.
If you're referring to the fact that non-main concurrent threads aren't required to terminate before the program terminates, then I think you're placing the wrong emphasis by saying that "bracket doesn't work with concurrent programs". It works fine. Are there any situations in which the cleanup action in a bracket might not run? Sure: * the bracket is in a non-main thread and the program terminates * SIGKILL, SIGSEGV, etc. * Out of memory (should be an exception, but isn't) * Power failure * etc. etc. should we therefore say that bracket doesn't work? I argue not. Cheers, Simon