Boolean-0.2.3: Generalized booleans and numbers

Data.Boolean

Description

Some classes for generalized boolean operations.

In this design, for if-then-else, equality and inequality tests, the boolean type depends on the value type.

I also tried using a unary type constructor class. The class doesn't work for regular booleans, so generality is lost. Also, we'd probably have to wire class constraints in like: (==*) :: Eq a => f Bool -> f a -> f a -> f a, which disallows situations needing additional constraints, e.g., Show.

Starting with 0.1.0, this package uses type families. Up to version 0.0.2, it used MPTCs with functional dependencies. My thanks to Andy Gill for suggesting & helping with the change.

Synopsis

Documentation

class Boolean b where Source

Generalized boolean class

Methods

true, false :: b Source

notB :: b -> b Source

(&&*), (||*) :: b -> b -> b infixr 3 &&*infixr 2 ||* Source

Instances

 Boolean Bool Boolean bool => Boolean (z -> bool)

type family BooleanOf a Source

BooleanOf computed the boolean analog of a specific type.

Instances

 type BooleanOf Bool = Bool type BooleanOf Char = Bool type BooleanOf Double = Bool type BooleanOf Float = Bool type BooleanOf Int = Bool type BooleanOf Integer = Bool type BooleanOf [a] = BooleanOf a type BooleanOf (z -> a) = z -> BooleanOf a type BooleanOf (a, b) = BooleanOf a type BooleanOf (a, b, c) = BooleanOf a type BooleanOf (a, b, c, d) = BooleanOf a

class Boolean (BooleanOf a) => IfB a where Source

Types with conditionals

Methods

ifB :: (bool ~ BooleanOf a) => bool -> a -> a -> a Source

Instances

 IfB Bool IfB Char IfB Double IfB Float IfB Int IfB Integer (Boolean (BooleanOf a), (~) * (BooleanOf a) Bool) => IfB [a] IfB a => IfB (z -> a) ((~) * bool (BooleanOf p), (~) * bool (BooleanOf q), IfB p, IfB q) => IfB (p, q) ((~) * bool (BooleanOf p), (~) * bool (BooleanOf q), (~) * bool (BooleanOf r), IfB p, IfB q, IfB r) => IfB (p, q, r) ((~) * bool (BooleanOf p), (~) * bool (BooleanOf q), (~) * bool (BooleanOf r), (~) * bool (BooleanOf s), IfB p, IfB q, IfB r, IfB s) => IfB (p, q, r, s)

boolean :: (IfB a, bool ~ BooleanOf a) => a -> a -> bool -> a Source

Expression-lifted conditional with condition last

cond :: (Applicative f, IfB a, bool ~ BooleanOf a) => f bool -> f a -> f a -> f a Source

Point-wise conditional

crop :: (Applicative f, Monoid (f a), IfB a, bool ~ BooleanOf a) => f bool -> f a -> f a Source

Generalized cropping, filling in mempty where the test yields false.

class Boolean (BooleanOf a) => EqB a where Source

Types with equality. Minimum definition: '(==*)'.

Minimal complete definition

(==*)

Methods

(==*), (/=*) :: (bool ~ BooleanOf a) => a -> a -> bool infix 4 ==*, /=* Source

Instances

 EqB Bool EqB Char EqB Double EqB Float EqB Int EqB Integer EqB a => EqB (z -> a)

class Boolean (BooleanOf a) => OrdB a where Source

Types with inequality. Minimum definition: '(<*)'.

Minimal complete definition

(<*)

Methods

(<*), (>=*), (>*), (<=*) :: (bool ~ BooleanOf a) => a -> a -> bool infix 4 <*, >=*, >*, <=* Source

Instances

 OrdB Bool OrdB Char OrdB Double OrdB Float OrdB Int OrdB Integer OrdB a => OrdB (z -> a)

minB :: (IfB a, OrdB a) => a -> a -> a Source

Variant of min using ifB and '(<=*)'

maxB :: (IfB a, OrdB a) => a -> a -> a Source

Variant of max using ifB and '(>=*)'

sort2B :: (IfB a, OrdB a) => (a, a) -> (a, a) Source

Variant of min and max using ifB and '(<=*)'

guardedB :: (IfB b, bool ~ BooleanOf b) => bool -> [(bool, b)] -> b -> b Source

A generalized replacement for guards and chained ifs.

caseB :: (IfB b, bool ~ BooleanOf b) => a -> [(a -> bool, b)] -> b -> b Source

A generalized version of a case like control structure.