Documentation

Generate predicates from constructor names or from quoted patterns.

We provide three implementations of the functions is and isNot, each relying on a different generic programming technique.

Template Haskell

Data.Generics.Is.TH. Most flexible and efficient, works on GADTs. Requires access to the type declaration; it can also declare predicate functions from each constructor of a given type.

Generics

Data.Generics.Is.Generic. Safe. Requires an instance of Generic. It performs faster than SYB, according to this StackOverflow answer.

Scrap Your Boilerplate

Data.Generics.Is.Data. Safe. Works only on monomorphic values. Requires an instance of Data.