:: String -> Int -package:hledger-lib -package:speculate -package:monads-tf -package:dbus -package:safe -package:string-conversions package:polysemy is:exact

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.