RE: STM check operation

| Thanks for your reply. I'm a bit confused, however. There is a | function | "check :: Bool -> STM a" in the STM library, but it appears to act | differently than the one described in the paper. This version of check | seems to cause a transaction to block when its (check's) first argument | is False, rather than issue an error or exception. Is this right?] True, alas. In 6.4.2, 'check' is defined thus: check :: Bool -> STM a check b = if b then return undefined else retry But in 6.6 that's changing to the new semantics described in the invariants paper. Sorry. Simon