NAME

Logic::Ternary — Ternary logic for Raku

SYNOPSIS

use Logic::Ternary;

my $t = True;
my $f = False;
my $u = Unknown;

# Negation
dd not3 $t;              # Logic::Ternary::False
dd not3 $u;              # Logic::Ternary::Unknown

# Conjunction/Disjunction/xor (operands are coerced to Ternary)
dd $t and3 $u;            # Logic::Ternary::Unknown
dd $t or3  $u;            # Logic::Ternary::True
dd $t xor3 $t;            # Logic::Ternary::False

# Coercions
dd  1 .Ternary;          # Logic::Ternary::True
dd -3 .Ternary;          # Logic::Ternary::False
dd  0 .Ternary;          # Logic::Ternary::Unknown
dd Bool::True.Ternary;   # Logic::Ternary::True
dd Bool.Ternary;         # Logic::Ternary::Unknown

DESCRIPTION

Logic::Ternary implements a three-valued logic for Raku:

• True (+1),

• Unknown (0),

• and False (-1).

Values are Logic::Ternary::True, Logic::Ternary::Unknown, and Logic::Ternary::False.

• Predicates: .is-true, .is-false, .is-unknown.

• Negation: not3 $x.

• Booleanization: Bool($x) is true only when $x is True.

• Coercion: Numeric.Ternary maps:

  • negatives→False,

  • zero→Unknown,

  • positives→True; Bool.Ternary preserves True/False and yields Unknown when undefined.

Operators

These operators always coerce both operands with .Ternary:

• and3: ternary conjunction.

• or3: ternary disjunction.

• xor3: defined as (A or3 B) and3 not3(A and3 B).

• not3: negation.

• so3: ternarisation.

Quick examples

use Logic::Ternary;

my $u = Unknown;

# and3 behavior
dd $u and3 True;   # Logic::Ternary::Unknown
dd $u and3 False;  # Logic::Ternary::False

# or3 behavior
dd True or3 $u;    # Logic::Ternary::True
dd $u or3 False;   # Logic::Ternary::Unknown

# Mixed types are coerced
dd 1 and3 0;       # Logic::Ternary::Unknown
dd -2 or3  1;      # Logic::Ternary::True

dd not3 1;         # Logic::Ternary::False

AUTHOR

Fernando Corrêa de Oliveira fco@cpan.org

COPYRIGHT AND LICENSE

Copyright 2025 Fernando Corrêa de Oliveira

This library is free software; you can redistribute it and/or modify it under the Artistic License 2.0.