Haskell: TVar: orElse

1.1k views Asked by At

Is the "else" part of orElse called when a transaction is retried due to another transaction writing to a TVar it had read, or only when retry is explicitly called?

1

There are 1 answers

0
Peter On BEST ANSWER

If you have

orElse a b

then b is only run if retry is called explicitly in a. Otherwise orElse would essentially become nondeterministic. (The rerunning of transactions that is done by the STM runtime is transparent and should not effect the outcome of any computation.)