Parsec is designed from scratch as an industrial-strength parser
library.  It is simple, safe, well documented, has extensive
libraries and good error messages, and is also fast.  It is defined
as a monad transformer that can be stacked on arbitrary monads, and
it is also parametric in the input stream type.

After uninstalling, run this command to unregister the package from
the ghc package database:   ghc-pkg recache