Test.LeanCheck.Derive

This module is part of LeanCheck, a simple enumerative property-based testing library.

This is an experimental module for deriving Listable instances.

Needs GHC and Template Haskell (tested on GHC 7.4, 7.6, 7.8, 7.10 and 8.0).

If LeanCheck does not compile under later GHCs, this module is probably the culprit.

Documentation

deriveListable :: Name -> DecsQ

Derives a Listable instance for a given type Name.

Consider the following Stack datatype:

data Stack a = Stack a (Stack a) | Empty

Writing

deriveListable ''Stack

will automatically derive the following Listable instance:

instance Listable a => Listable (Stack a) where
  tiers = cons2 Stack \/ cons0 Empty

Needs the TemplateHaskell extension.

deriveListableIfNeeded :: Name -> DecsQ

Same as deriveListable but does not warn when instance already exists (deriveListable is preferable).

deriveListableCascading :: Name -> DecsQ

Derives a Listable instance for a given type Name cascading derivation of type arguments as well.

deriveTiers :: Name -> ExpQ

deriveList :: Name -> ExpQ