logical

Module nu.core.logical.

Logical atoms: Python's boolean operators and truthiness.

Maps Python's boolean operations onto Nu ScalarQueries. Pure compute; no Context effect of their own.

Builtins / operators to cover (Python -> Nu):

• and -> And, or -> Or, not -> Not
• bool (truthiness) -> ToBool

Sorts: all ScalarQuery (Q). And / Or are variadic; Not and ToBool are unary. logical owns ToBool; cast does not define it.

And / Or semantics: Python's and / or short-circuit and return an operand (not a bool). Nu short-circuits the same way but always coerces to bool, so a Nu And / Or yields a plain boolean while leaving the operands past the deciding one unevaluated. That is what makes them usable as guards: And(not_empty(x), contains(x)) never runs contains when x is empty. And yields True over no operands, Or yields False.

Sentinels: every operand that is actually evaluated is checked; an EMPTY or INVALID operand collapses the whole query to INVALID (per nu.lang.sentinels). Short-circuit wins over sentinel poisoning - an operand that is never evaluated can never poison the result.

And

The conjunction of its boolean children, each coerced with bool.

And(*children)

Path nu.core.And. Kind ScalarQuery, sort scalar_query, cardinality scalar. Arity None (0 required).

Arguments

Yields

A plain bool. INVALID when an evaluated child is EMPTY or INVALID.

Notes

• Short-circuits like Python's and: the first falsy child decides the result and the children after it are never evaluated. This is what lets And guard - a guard that still runs the thing it is guarding is not a guard.
• Short-circuit beats sentinel poisoning: a child that is never evaluated never contributes its sentinel, so And(False, <INVALID>) is False, not INVALID.
• No children at all yields True.

Example

nu.run(nu.And(True, True))[0]
nu.run(nu.And(True, False))[0]

True
False

Not

The negation of its one child.

Not(value)

Path nu.core.Not. Kind ScalarQuery, sort scalar_query, cardinality scalar. Arity 1 (1 required).

Arguments

Yields

A plain bool. INVALID when the child is EMPTY or INVALID.

Example

nu.run(nu.Not(True))[0]

False

Or

The disjunction of its boolean children, each coerced with bool.

Or(*children)

Path nu.core.Or. Kind ScalarQuery, sort scalar_query, cardinality scalar. Arity None (0 required).

Arguments

Yields

A plain bool. INVALID when an evaluated child is EMPTY or INVALID.

Notes

• Short-circuits like Python's or: the first truthy child decides the result and the children after it are never evaluated. This is what lets Or guard - a guard that still runs the thing it is guarding is not a guard.
• Short-circuit beats sentinel poisoning: a child that is never evaluated never contributes its sentinel, so Or(True, <INVALID>) is True, not INVALID.
• No children at all yields False.

Example

nu.run(nu.Or(False, True))[0]
nu.run(nu.Or(False, False))[0]

True
False

ToBool

The truthiness of its one child.

ToBool(value)

Path nu.core.ToBool. Kind ScalarQuery, sort scalar_query, cardinality scalar. Arity 1 (1 required).

Arguments

Yields

A plain bool. INVALID when the child is EMPTY or INVALID.

Example

nu.run(nu.core.logical.ToBool(0))[0]

False

bool

Coerce x to a Nu Bool term.

core.bool(x)

Path nu.core.bool. Defined on nu.core.logical, bound as a function. Builds object.

Arguments

Yields

A Nu Bool.

Notes

• Bool(ToBool(x)) in one call: Form-wraps the raw ToBool atom so the result composes like any other Nu term.

Example

nu.run(nu.core.logical.bool(1))[0]

True