Subtypable Boolean

Like the Python builtin type bool, but subtypable.

class pythonic_fp.booleans.subtypable.SBool

Bases: int

Subtypable Boolean

Like Python’s built in bool, class SBool is a singleton subclass of int. Unlike bool, it can be further subclassed.

SBool and its subtypes can also do (non-shortcut) Boolean logic using Python bitwise operators.

Boolean operation	symbol	dunder
not	~	__invert__
and	&	__and__
or	|	__or__
xor	^	__xor__

While compatible with Python short-cut logic, , the not operator unfortunately always returns a bool.

Tip

Use the bitwise ~ operator to return an opposite SBool instance or subclass instance.

Note

These operators are contravariant, that is they will return the instance of the latest common ancestor of their arguments. More specifically, the instance returned will have the type of the least upper bound in the inheritance graph of the classes of the two arguments.

Warning

The “bitwise” operators can raise TypeError exceptions when applied against an SBool and objects not descended from int.

static __new__(cls, witness: object) → Self

static __new__(cls, witness: object, flavor: Hashable | NoValue = no_value) → Self

new

param witness:

Determines truthiness of the SBool.

param flavor:

Ignored, here for Liskov substitution principle

returns:

The truthy or falsy SBool class instance.

__init__(witness: object) → None

__init__(witness: object, flavor: Hashable) → None

init

param witness:

Determines the truthiness of the SBool.

param flavor:

Ignored by SBool, here only to support the Liskov Substitution Principle.

__invert__() → int

bitwise invert operator

Inverts the value of an SBool.

returns:

The inverted value of the SBool.

__and__(other: int) → int

bitwise and operator

Overloading & to perform Boolean “and” if other is another SBool.

param other:

Any object derived from int.

returns:

Boolean “and” if other is an SBool otherwise returns bitwise “and”.

rtype:

First common ancestor of the types of self and other if both of type SBool, otherwise int.

__or__(other: int) → int

bitwise or operator

Overloading | to perform Boolean “or” if other is another SBool.

param other:

Any object derived from int.

returns:

Boolean “and” if other is an SBool otherwise returns bitwise “and”.

rtype:

First common ancestor of the types of self and other if both of type SBool, otherwise int.

__xor__(other: int) → int

bitwise xor operator

Overloading ^ to perform Boolean “xor” if other is another SBool.

param other:

Any object derived from int.

returns:

Boolean “and” if other is an SBool otherwise returns bitwise “and”.

rtype:

First common ancestor of the types of self and other if both of type SBool, otherwise int.

__repr__() → str

repr string

A string to reproduce the SBool.

returns:

‘SBool(True)’ if truthy, ‘SBool(False)’ if falsy.

__str__() → str

user string

A string meaningful to an end user.

returns:

‘TRUTH’ if truthy, ‘LIE’ if falsy.

pythonic_fp.booleans.subtypable.TRUTH: Final[SBool] = SBool(True)

TRUTH

var TRUTH:

The truthy singleton of type SBool.

pythonic_fp.booleans.subtypable.LIE: Final[SBool] = SBool(False)

LIE

var LIE:

The falsy singleton of type SBool.