Three-valued logic: conjunction, disjunction, and negation (DMN 1.6, section 10.3.2.4 and Tables 51 and 52).
The operations are total. An operand is true, false, or "otherwise", which
means any other value, null included:
| a | b | a and b | a or b |
|---|---|---|---|
| true | true | true | true |
| true | false | false | true |
| true | otherwise | null | true |
| false | true | false | true |
| false | false | false | false |
| false | otherwise | false | null |
| otherwise | true | null | true |
| otherwise | false | false | null |
| otherwise | otherwise | null | null |
not is true for false, false for true, and null otherwise. The result
does not depend on the order of the operands, so a chain a and b and c has one
value however it is grouped. A false decides a conjunction and a true decides
a disjunction whatever the other operand is, an error included.
A result of null is not an error of and and or: the tables give null for an operand that is
neither a boolean nor null too, as in true and "x", and the TCK flags none of the cases of
0064 and 0065 (D-103). It is one of not for a value that is neither a boolean nor null, which is a
call of a function with an argument out of its domain (0066#003_b to #003_d).
The functions are named after the tables because and, or, and not are
Elixir operators.
Summary
Functions
Returns the conjunction of two values.
Returns the disjunction of two values.
Returns the negation of a value.
Functions
@spec conjunction(Feel.Value.t(), Feel.Value.t()) :: Feel.Runtime.Env.outcome()
Returns the conjunction of two values.
iex> Feel.Runtime.Logic.conjunction(true, false)
{:ok, false}
iex> Feel.Runtime.Logic.conjunction(false, nil)
{:ok, false}
iex> Feel.Runtime.Logic.conjunction(true, nil)
:missing@spec disjunction(Feel.Value.t(), Feel.Value.t()) :: Feel.Runtime.Env.outcome()
Returns the disjunction of two values.
iex> Feel.Runtime.Logic.disjunction(nil, true)
{:ok, true}
iex> Feel.Runtime.Logic.disjunction(false, false)
{:ok, false}
iex> Feel.Runtime.Logic.disjunction(false, "x")
:missing@spec negation(Feel.Value.t()) :: Feel.Runtime.Env.outcome()
Returns the negation of a value.
iex> Feel.Runtime.Logic.negation(true)
{:ok, false}
iex> Feel.Runtime.Logic.negation(nil)
:missing