:: String -> Int is:exact -package:Cabal -package:monads-tf -package:ghc-lib-parser -package:speculate -package:string-conversions 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.