-- | -- Module : Test.LeanCheck.Function.Ord -- Copyright : (c) 2015-2021 Rudy Matela -- License : 3-Clause BSD (see the file LICENSE) -- Maintainer : Rudy Matela <rudy@matela.com.br> -- -- This /optional/ module is part of LeanCheck, -- a simple enumerative property-based testing library. -- -- Toy 'Eq' and 'Ord' instance for functions. -- -- > instance (Listable a, Eq b) => Eq (a -> b) where -- > (==) = areEqualFor 12 -- -- > instance (Listable a, Ord b) => Ord (a -> b) where -- > compare = compareFor 12 -- -- This compares functions by testing them -- for up to 12 different values of each argument. -- -- Single argument functions are tested 12 times. -- Two argument functions are tested 144 times. -- Three argument functions are tested 1728 times. -- At each subsequent argument, -- number of tests and runtime increases 12-fold. -- -- To customize the number of tests, -- don't import this and use the above code changing the @12@ value. -- Keep in mind that this value is number of tests for /each/ argument. -- -- __Warning:__ -- this is only intended to be used in testing modules. -- Avoid importing this on modules that are used as libraries -- as there is no way to unimport a typeclass instance. module Test.LeanCheck.Function.Ord () where import Test.LeanCheck.Core import Test.LeanCheck.Function.List import Test.LeanCheck.Function.Eq () -- | Two functions are compared based on the results -- of twelve different enumerated values for each argument. -- -- Single argument functions are tested 12 times. -- Two argument functions are tested 144 times. -- Three argument functions are tested 1728 times. -- At each subsequent argument, -- number of tests and runtime increases 12-fold. -- -- This is only intended to be available on test programs and modules -- but not on libraries. If you see this exported on a library -- that is not specifically intended to consider equality between -- functions, file a bug report to the library maintainer. instance (Listable a, Ord b) => Ord (a -> b) where compare :: (a -> b) -> (a -> b) -> Ordering compare = Int -> (a -> b) -> (a -> b) -> Ordering forall a b. (Listable a, Ord b) => Int -> (a -> b) -> (a -> b) -> Ordering compareFor Int 12