:: String -> Int is:exact -package:safe -package:speculate -package:hxt -package:dbus -package:Cabal -package:hledger-lib package:polysemy

The error used in fixpointToFinal, runFixpoint and runFixpointM when the result of a failed computation is recursively used and somehow visible. You may use this for your own Fixpoint interpreters. The argument should be the name of the interpreter.