:: String -> Int -package:hledger-lib -package:speculate -package:monads-tf package:polysemy -is:exact -is:exact 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.