libghc-safe-dev binary package in Ubuntu Focal amd64

 .
 Partial functions from the base library, such as head and !!, modified to
 return more descriptive error messages, programmer defined error messages,
 Maybe wrapped results and default values. These functions can be used to
 reduce the number of unsafe pattern matches in your code.
 .
 This package provides a library for the Haskell programming language.
 See http://www.haskell.org/ for more information on Haskell.

Source package