:: String -> Int is:exact -package:gpolyline -package:numeric-prelude -package:ghc-lib-parser -package:vty -package:speculate 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.