Test.Operators

Combining properties

(===) :: Eq b => (a -> b) -> (a -> b) -> a -> Bool infix 4

(====) :: Eq c => (a -> b -> c) -> (a -> b -> c) -> a -> b -> Bool infix 4

(&&&) :: (a -> Bool) -> (a -> Bool) -> a -> Bool infix 3

(&&&&) :: (a -> b -> Bool) -> (a -> b -> Bool) -> a -> b -> Bool infix 3

(|||) :: (a -> Bool) -> (a -> Bool) -> a -> Bool infix 2

(||||) :: (a -> b -> Bool) -> (a -> b -> Bool) -> a -> b -> Bool infix 2

Properties over functions

commutative :: Eq b => (a -> a -> b) -> a -> a -> Bool

associative :: Eq a => (a -> a -> a) -> a -> a -> a -> Bool

distributive :: Eq a => (a -> a -> a) -> (a -> a -> a) -> a -> a -> a -> Bool

transitive :: (a -> a -> Bool) -> a -> a -> a -> Bool

idempotent :: Eq a => (a -> a) -> a -> Bool

identity :: Eq a => (a -> a) -> a -> Bool

notIdentity :: Eq a => (a -> a) -> a -> Bool

Ternary comparison operators

(=$) :: Eq b => a -> (a -> b) -> a -> Bool infixl 4

Equal under. A ternary operator.

x =$ f $= y  =  f x = f y

[1,2,3,4,5] =$  take 2    $= [1,2,4,8,16] -- > True
[1,2,3,4,5] =$  take 3    $= [1,2,4,8,16] -- > False
    [1,2,3] =$    sort    $= [3,2,1]      -- > True
         42 =$ (`mod` 10) $= 16842        -- > True
         42 =$ (`mod`  9) $= 16842        -- > False
        'a' =$  isLetter  $= 'b'          -- > True
        'a' =$  isLetter  $= '1'          -- > False

($=) :: (a -> Bool) -> a -> Bool infixl 4

(=|) :: Eq a => [a] -> Int -> [a] -> Bool infixl 4

Check if two lists are equal for n values.

xs =| n |= ys  =  take n xs == take n ys

[1,2,3,4,5] =| 2 |= [1,2,4,8,16] -- > True
[1,2,3,4,5] =| 3 |= [1,2,4,8,16] -- > False

(|=) :: (a -> Bool) -> a -> Bool infixl 4