attrs.refs

Module nu.context.attrs.refs.

AttrRef and its typed variants.

An AttrRef names a slot in ctx.attrs by its resolved address (any child that yields a value). Reads self-yield the value at that key (EMPTY when unbound); writes and erases go through the Ref so a Command never touches ctx.attrs directly - the write mechanism lives with the fabric.

Name	Sort	Call	Meaning
AnyAttrRef	`ref`	`AnyAttrRef()`	An AttrRef with the dynamic any interface.
AttrRef	`ref`	`AttrRef(address)`	A Ref into the `ctx.attrs` store, keyed by its resolved address.
BoolAttrRef	`ref`	`BoolAttrRef()`	An AttrRef with the full boolean interface.
BytesAttrRef	`ref`	`BytesAttrRef()`	An AttrRef with the full bytes interface.
DictAttrRef	`ref`	`DictAttrRef()`	An AttrRef with the full dict interface.
FloatAttrRef	`ref`	`FloatAttrRef()`	An AttrRef with the full float interface.
FrozenSetAttrRef	`ref`	`FrozenSetAttrRef()`	An AttrRef with the full frozenset interface.
IntAttrRef	`ref`	`IntAttrRef()`	An AttrRef with the full integer interface.
ListAttrRef	`ref`	`ListAttrRef()`	An AttrRef with the full list interface.
NoneAttrRef	`ref`	`NoneAttrRef(source=None)`	An AttrRef with the none interface.
SetAttrRef	`ref`	`SetAttrRef()`	An AttrRef with the full set interface.
StrAttrRef	`ref`	`StrAttrRef()`	An AttrRef with the full string interface.
TupleAttrRef	`ref`	`TupleAttrRef()`	An AttrRef with the full tuple interface.

AnyAttrRef

An AttrRef with the dynamic any interface.

AnyAttrRef()

Path nu.context.AnyAttrRef. Kind Ref, sort ref, cardinality scalar.

Inherited methods

From nu.context.attrs.refs.AttrRef:

Call	Builds	Meaning
`.exists()`	`AttrExists`	A Query yielding whether this Ref's address is bound in `ctx.attrs`.

From nu.forms.primitives.any_.Any:

Call	Builds	Meaning
`a + b`	`Any`	Sum of self and other.
`a - b`	`Any`	Self minus other.
`a * b`	`Any`	Product of self and other.
`a @ b`	`Any`	Matrix multiplication: self @ other.
`a / b`	`Any`	Self divided by other.
`a // b`	`Any`	Self floor-divided by other.
`a % b`	`Any`	Self modulo other.
`a ** b`	`Any`	Self raised to the other power.
`-a`	`Any`	Negation of self.
`+a`	`Any`	Self unchanged.
`abs(a)`	`Any`	Absolute value of self.
`a > b`	`Bool`	Self strictly greater than other.
`a < b`	`Bool`	Self strictly less than other.
`a >= b`	`Bool`	Self greater than or equal to other.
`a <= b`	`Bool`	Self less than or equal to other.
`a == b`	`Bool`	Self equal to other by value.
`a != b`	`Bool`	Self not equal to other by value.
`.is_(other)`	`Bool`	Identity comparison: self is other.
`.and_(other)`	`Bool`	Logical AND of self and other.
`.or_(other)`	`Bool`	Logical OR of self and other.
`.not_()`	`Bool`	Logical NOT of self.
`.bool_()`	`Bool`	Cast self to Bool.
`.bitand(other)`	`Any`	Bitwise AND: self & other.
`.bitor(other)`	`Any`	Bitwise OR: self \| other.
`.bitnot()`	`Any`	Bitwise NOT: ~self.
`~a`	`Any`	Bitwise NOT: ~self.
`a ^ b`	`Any`	Bitwise XOR: self ^ other.
`a << b`	`Any`	Left shift: self shifted left by other bits.
`a >> b`	`Any`	Right shift: self shifted right by other bits.
`a[key]`	`Any`	Subscript access: self[key].
`a[key] = value`	`object`	Subscript write: self[key] = value.
`.len_()`	`Int`	Length of self, as len(self).
`.contains(item)`	`Bool`	Membership test: item in self.
`.iter_()`	`Iterator`	Iterator over self, as iter(self).
`.has_attr(name)`	`Bool`	Attribute presence: hasattr(self, name).

From nu.lang.forms.Form:

Call	Builds	Meaning
`.is_empty()`	`Bool`	True if this Form yields the EMPTY sentinel.
`.is_invalid()`	`Bool`	True if this Form yields the INVALID sentinel.
`.is_sentinel()`	`Bool`	True if this Form yields either sentinel (EMPTY or INVALID).
`.not_empty()`	`Bool`	True if this Form does not yield EMPTY.
`.not_invalid()`	`Bool`	True if this Form does not yield INVALID.

Undocumented: example.

AttrRef

A Ref into the ctx.attrs store, keyed by its resolved address.

AttrRef(address)

Path nu.context.AttrRef. Kind Ref, sort ref, cardinality scalar.

The sole child is the address, evaluated through the runtime like any other child, so a key can be fixed at write time or computed at run time. Reading is the dual role: the Ref self-yields whatever sits at that key. Writing and erasing never happen at the call site - a Command hands the Ref its own node id, the Ref resolves its address and touches the store, so the write mechanism stays with the fabric.

Notes

An unbound slot and a slot holding EMPTY read the same, so reach for .exists() when the difference matters.
ctx.attrs is the short-lived axis of the Context fabric: loop variables, counters, accumulators, markers. Anything longer-lived is a typed binding, read through FabricRef.
Map and Filter bind their per-item loop variable into this same store, which is why a body reads the item with an AttrRef.
The typed variants mix a Form in for its operator surface only. Nothing checks that the value at the key really has that type; an IntAttrRef over an unbound slot yields EMPTY, and arithmetic on it collapses to INVALID like any other sentinel operand.

Examples

nu.run(nu.AttrRef("missing"))[0]

<EMPTY>

nu.run(nu.SetCmd(nu.AttrRef("total"), 10))[1].attrs

Attributes(total=10)

key = nu.SetCmd(nu.AttrRef("k"), "total")
nu.run(nu.Sequential(key, nu.SetCmd(nu.AttrRef(nu.AttrRef("k")), 5)))[1].attrs

Attributes(k='total', total=5)

Methods

`.exists()`

A Query yielding whether this Ref's address is bound in ctx.attrs.

Builds AttrExists.

Notes

The plain read cannot answer this: an unbound slot yields EMPTY and so does a slot bound to EMPTY.
Only the address is resolved; the slot's value is never read.

Undocumented: example.

BoolAttrRef

An AttrRef with the full boolean interface.

BoolAttrRef()

Path nu.context.BoolAttrRef. Kind Ref, sort ref, cardinality scalar.

Inherited methods

From nu.context.attrs.refs.AttrRef:

Call	Builds	Meaning
`.exists()`	`AttrExists`	A Query yielding whether this Ref's address is bound in `ctx.attrs`.

From nu.forms.primitives.bool_.Bool:

Call	Builds	Meaning
`.and_(other)`	`Bool`	Logical AND of self and other.
`.or_(other)`	`Bool`	Logical OR of self and other.
`.not_()`	`Bool`	Logical NOT of self.
`.bool_()`	`Bool`	Cast self to Bool.
`a > b`	`Bool`	Self strictly greater than other.
`a < b`	`Bool`	Self strictly less than other.
`a >= b`	`Bool`	Self greater than or equal to other.
`a <= b`	`Bool`	Self less than or equal to other.
`a == b`	`Bool`	Self equal to other by value.
`a != b`	`Bool`	Self not equal to other by value.
`.is_(other)`	`Bool`	Identity comparison: self is other.

From nu.lang.forms.Form:

Call	Builds	Meaning
`.is_empty()`	`Bool`	True if this Form yields the EMPTY sentinel.
`.is_invalid()`	`Bool`	True if this Form yields the INVALID sentinel.
`.is_sentinel()`	`Bool`	True if this Form yields either sentinel (EMPTY or INVALID).
`.not_empty()`	`Bool`	True if this Form does not yield EMPTY.
`.not_invalid()`	`Bool`	True if this Form does not yield INVALID.

Undocumented: example.

BytesAttrRef

An AttrRef with the full bytes interface.

BytesAttrRef()

Path nu.context.BytesAttrRef. Kind Ref, sort ref, cardinality scalar.

Inherited methods

From nu.context.attrs.refs.AttrRef:

Call	Builds	Meaning
`.exists()`	`AttrExists`	A Query yielding whether this Ref's address is bound in `ctx.attrs`.

From nu.forms.primitives.bytes_.Bytes:

Call	Builds	Meaning
`a + b`	`Bytes`	Concatenation of self and other.
`a[key]`	`Bytes \| Int`	Byte at an index, or a sub-range by slice.
`a > b`	`Bool`	Self strictly greater than other.
`a < b`	`Bool`	Self strictly less than other.
`a >= b`	`Bool`	Self greater than or equal to other.
`a <= b`	`Bool`	Self less than or equal to other.
`a == b`	`Bool`	Self equal to other by value.
`a != b`	`Bool`	Self not equal to other by value.
`.is_(other)`	`Bool`	Identity comparison: self is other.
`.and_(other)`	`Bool`	Logical AND of self and other.
`.or_(other)`	`Bool`	Logical OR of self and other.
`.not_()`	`Bool`	Logical NOT of self.
`.bool_()`	`Bool`	Cast self to Bool.
`.decode(encoding='utf-8')`	`Str`	Decode self to a string using the given encoding.
`.hex_()`	`Str`	Hex string of self, two digits per byte.
`.upper()`	`Bytes`	Self with ASCII letters uppercased.
`.lower()`	`Bytes`	Self with ASCII letters lowercased.
`.strip(chars=None)`	`Bytes`	Self with leading and trailing bytes removed.
`.lstrip(chars=None)`	`Bytes`	Self with leading bytes removed.
`.rstrip(chars=None)`	`Bytes`	Self with trailing bytes removed.
`.split_bytes(sep=None, maxsplit=-1)`	`List`	Self split into a List of Bytes on sep.
`.find_bytes(sub, start=0, end=None)`	`Int`	Lowest index of sub in self, or -1 if absent.
`.count_bytes(sub)`	`Int`	Number of non-overlapping occurrences of sub in self.
`.startswith(prefix)`	`Bool`	Self starts with prefix.
`.endswith(suffix)`	`Bool`	Self ends with suffix.
`.replace(old, new, count=-1)`	`Bytes`	Self with occurrences of old replaced by new.
`.removeprefix(prefix)`	`Bytes`	Self with prefix removed if present.
`.removesuffix(suffix)`	`Bytes`	Self with suffix removed if present.
`.translate(table, delete=b'')`	`Bytes`	Self translated through a 256-byte table, with bytes in delete dropped first.
`.title()`	`Bytes`	Self titlecased: each word's first cased byte upper, the rest lower.
`.capitalize()`	`Bytes`	Self with the first byte uppercased and the rest lowercased.
`.swapcase()`	`Bytes`	Self with uppercase and lowercase bytes swapped.
`.rsplit_bytes(sep=None, maxsplit=-1)`	`List`	Self split into a List of Bytes on sep, counting maxsplit from the right.
`.splitlines(keepends=False)`	`List`	Self split into a List of Bytes at line boundaries.
`.partition(sep)`	`Tuple`	Self split around the first occurrence of sep.
`.rpartition(sep)`	`Tuple`	Self split around the last occurrence of sep.
`.rfind_bytes(sub, start=0, end=None)`	`Int`	Highest index of sub in self, or -1 if absent.
`.index_bytes(sub, start=0, end=None)`	`Int`	Lowest index of sub in self.
`.rindex_bytes(sub, start=0, end=None)`	`Int`	Highest index of sub in self.
`.isascii()`	`Bool`	Self has only ASCII bytes.
`.isdigit()`	`Bool`	Self has only ASCII digit bytes, and at least one.
`.isalpha()`	`Bool`	Self has only ASCII letter bytes, and at least one.
`.isalnum()`	`Bool`	Self has only ASCII alphanumeric bytes, and at least one.
`.isspace()`	`Bool`	Self has only ASCII whitespace bytes, and at least one.
`.istitle()`	`Bool`	Self is titlecased, with at least one cased byte.
`.isupper()`	`Bool`	Self has all cased bytes uppercase, and at least one cased byte.
`.islower()`	`Bool`	Self has all cased bytes lowercase, and at least one cased byte.
`.center(width, fillbyte=b' ')`	`Bytes`	Self centered in a field of width, padded with fillbyte.
`.ljust(width, fillbyte=b' ')`	`Bytes`	Self left-justified in a field of width, padded with fillbyte.
`.rjust(width, fillbyte=b' ')`	`Bytes`	Self right-justified in a field of width, padded with fillbyte.
`.zfill(width)`	`Bytes`	Self padded with leading zero bytes to width.
`.expandtabs(tabsize=8)`	`Bytes`	Self with tab bytes expanded to spaces.
`.join(iterable)`	`Bytes`	Self used as separator between the elements of iterable.

From nu.lang.forms.Form:

Call	Builds	Meaning
`.is_empty()`	`Bool`	True if this Form yields the EMPTY sentinel.
`.is_invalid()`	`Bool`	True if this Form yields the INVALID sentinel.
`.is_sentinel()`	`Bool`	True if this Form yields either sentinel (EMPTY or INVALID).
`.not_empty()`	`Bool`	True if this Form does not yield EMPTY.
`.not_invalid()`	`Bool`	True if this Form does not yield INVALID.

Undocumented: example.

DictAttrRef

An AttrRef with the full dict interface.

DictAttrRef()

Path nu.context.DictAttrRef. Kind Ref, sort ref, cardinality scalar.

Inherited methods

From nu.context.attrs.refs.AttrRef:

Call	Builds	Meaning
`.exists()`	`AttrExists`	A Query yielding whether this Ref's address is bound in `ctx.attrs`.

From nu.forms.collections.dict_.Dict:

Call	Builds	Meaning
`DictAttrRef.create()`	`Dict[K, V]`	Fresh empty dict.
`DictAttrRef.of(fields)`	`Dict[str, V]`	Dict built from named field expressions.
`a[key]`		Value at key.
`.keys()`	`DictKeys[K]`	Self's keys as a live view.
`.values()`	`DictValues[V]`	Self's values as a live view.
`.items()`	`DictItems[K, V]`	Self's key-value pairs as a live view.
`a > b`	`Bool`	Self strictly greater than other.
`a < b`	`Bool`	Self strictly less than other.
`a >= b`	`Bool`	Self greater than or equal to other.
`a <= b`	`Bool`	Self less than or equal to other.
`a == b`	`Bool`	Self equal to other by value.
`a != b`	`Bool`	Self not equal to other by value.
`.is_(other)`	`Bool`	Identity comparison: self is other.

From nu.forms.collections.abc.mapping.MutableMappingForm:

Call	Builds	Meaning
`.set_item(key, value)`	`Any`	Set the value at key, inserting the key if it's missing: mapping[key] = value.
`.del_item(key)`	`Any`	Delete the entry at key: del mapping[key].
`.update(other)`	`Any`	Write other's entries into self, in place: mapping.update(other).
`.pop(key, default=None)`	`ValueResultT`	Remove key and yield its value, or default if key is missing.
`.popitem()`	`ValueResultT`	Remove and yield an arbitrary (key, value) pair: mapping.popitem().
`.setdefault(key, default=None)`	`ValueResultT`	Value at key, inserting default there first if key is missing.
`.merge_update(other)`	`CollectionResultT`	Merge other into self in place, and yield self: mapping \|= other.
`.clear()`	`Any`	Remove all entries: mapping.clear().

From nu.forms.collections.abc.mapping.MappingForm:

Call	Builds	Meaning
`.get_item(key, default=None)`	`ValueResultT`	Value at key, falling back to default: mapping.get_item(key, default).
`.copy()`	`CollectionResultT`	Shallow copy of self: mapping.copy().
`.reversed_keys()`	`CollectionResultT`	Keys in reverse insertion order: reversed(mapping).
`.reversed_values()`	`CollectionResultT`	Values in reverse insertion order: reversed(mapping.values()).
`.reversed_items()`	`CollectionResultT`	(key, value) pairs in reverse insertion order: reversed(mapping.items()).
`.merge(other)`	`CollectionResultT`	Self and other merged into a new mapping: mapping \| other.

From nu.forms.collections.abc.collection.CollectionForm:

Call	Builds	Meaning
`.extract()`	`object`	Materialise the full subtree rooted at self.

From nu.forms.collections.abc.sized.SizedForm:

Call	Builds	Meaning
`.len()`	`Int`	Length of self.

From nu.forms.collections.abc.iterable.IterableForm:

Call	Builds	Meaning
`iter(a)`	`Iterator[ElementT]`	Open self into a lazy iterator stream (Python's `iter`).

From nu.forms.collections.abc.container.ContainerForm:

Call	Builds	Meaning
`.contains(item)`	`Bool`	Whether item is a member of self.

From nu.lang.forms.Form:

Call	Builds	Meaning
`.is_empty()`	`Bool`	True if this Form yields the EMPTY sentinel.
`.is_invalid()`	`Bool`	True if this Form yields the INVALID sentinel.
`.is_sentinel()`	`Bool`	True if this Form yields either sentinel (EMPTY or INVALID).
`.not_empty()`	`Bool`	True if this Form does not yield EMPTY.
`.not_invalid()`	`Bool`	True if this Form does not yield INVALID.

Undocumented: example.

FloatAttrRef

An AttrRef with the full float interface.

FloatAttrRef()

Path nu.context.FloatAttrRef. Kind Ref, sort ref, cardinality scalar.

Inherited methods

From nu.context.attrs.refs.AttrRef:

Call	Builds	Meaning
`.exists()`	`AttrExists`	A Query yielding whether this Ref's address is bound in `ctx.attrs`.

From nu.forms.primitives.float_.Float:

Call	Builds	Meaning
`a + b`	`Float`	Sum of self and other.
`a - b`	`Float`	Self minus other.
`a * b`	`Float`	Product of self and other.
`a / b`	`Float`	Self divided by other.
`a // b`	`Float`	Self floor-divided by other.
`a % b`	`Float`	Self modulo other.
`a ** b`	`Float`	Self raised to the other power.
`-a`	`Float`	Negation of self.
`+a`	`Float`	Self unchanged.
`abs(a)`	`Float`	Absolute value of self.
`a > b`	`Bool`	Self strictly greater than other.
`a < b`	`Bool`	Self strictly less than other.
`a >= b`	`Bool`	Self greater than or equal to other.
`a <= b`	`Bool`	Self less than or equal to other.
`a == b`	`Bool`	Self equal to other by value.
`a != b`	`Bool`	Self not equal to other by value.
`.is_(other)`	`Bool`	Identity comparison: self is other.
`.and_(other)`	`Bool`	Logical AND of self and other.
`.or_(other)`	`Bool`	Logical OR of self and other.
`.not_()`	`Bool`	Logical NOT of self.
`.bool_()`	`Bool`	Cast self to Bool.

From nu.lang.forms.Form:

Call	Builds	Meaning
`.is_empty()`	`Bool`	True if this Form yields the EMPTY sentinel.
`.is_invalid()`	`Bool`	True if this Form yields the INVALID sentinel.
`.is_sentinel()`	`Bool`	True if this Form yields either sentinel (EMPTY or INVALID).
`.not_empty()`	`Bool`	True if this Form does not yield EMPTY.
`.not_invalid()`	`Bool`	True if this Form does not yield INVALID.

Undocumented: example.

FrozenSetAttrRef

An AttrRef with the full frozenset interface.

FrozenSetAttrRef()

Path nu.context.FrozenSetAttrRef. Kind Ref, sort ref, cardinality scalar.

Inherited methods

From nu.context.attrs.refs.AttrRef:

Call	Builds	Meaning
`.exists()`	`AttrExists`	A Query yielding whether this Ref's address is bound in `ctx.attrs`.

From nu.forms.collections.set_.FrozenSet:

Call	Builds	Meaning
`FrozenSetAttrRef.create()`	`FrozenSet[T]`	Build an empty frozenset.
`FrozenSetAttrRef.of(*items)`	`FrozenSet`	Build a frozenset from positional item expressions.
`a > b`	`Bool`	Self is a proper superset of other.
`a < b`	`Bool`	Self is a proper subset of other.
`a >= b`	`Bool`	Self is a superset of other, or equal.
`a <= b`	`Bool`	Self is a subset of other, or equal.
`a == b`	`Bool`	Self equal to other by value.
`a != b`	`Bool`	Self not equal to other by value.
`.is_(other)`	`Bool`	Identity comparison: self is other.

From nu.forms.collections.abc.set_.SetLikeForm:

Call	Builds	Meaning
`.union(other)`	`CollectionResultT`	Union of self and other.
`.intersection(other)`	`CollectionResultT`	Intersection of self and other.
`.difference(other)`	`CollectionResultT`	Elements of self that are not in other.
`.symmetric_difference(other)`	`CollectionResultT`	Elements in exactly one of self and other, not both.
`.issubset(other)`	`Bool`	Whether every element of self is in other.
`.issuperset(other)`	`Bool`	Whether every element of other is in self.
`.isdisjoint(other)`	`Bool`	Whether self and other share no elements.
`.copy()`	`CollectionResultT`	Shallow copy of self.
`a \| b`	`CollectionResultT`	Union: self \| other.
`a & b`	`CollectionResultT`	Intersection: self & other.
`a - b`	`CollectionResultT`	Difference: self - other.
`a ^ b`	`CollectionResultT`	Symmetric difference: self ^ other.

From nu.forms.collections.abc.collection.CollectionForm:

Call	Builds	Meaning
`.extract()`	`object`	Materialise the full subtree rooted at self.

From nu.forms.collections.abc.sized.SizedForm:

Call	Builds	Meaning
`.len()`	`Int`	Length of self.

From nu.forms.collections.abc.iterable.IterableForm:

Call	Builds	Meaning
`iter(a)`	`Iterator[ElementT]`	Open self into a lazy iterator stream (Python's `iter`).

From nu.forms.collections.abc.container.ContainerForm:

Call	Builds	Meaning
`.contains(item)`	`Bool`	Whether item is a member of self.

From nu.lang.forms.Form:

Call	Builds	Meaning
`.is_empty()`	`Bool`	True if this Form yields the EMPTY sentinel.
`.is_invalid()`	`Bool`	True if this Form yields the INVALID sentinel.
`.is_sentinel()`	`Bool`	True if this Form yields either sentinel (EMPTY or INVALID).
`.not_empty()`	`Bool`	True if this Form does not yield EMPTY.
`.not_invalid()`	`Bool`	True if this Form does not yield INVALID.

Undocumented: example.

IntAttrRef

An AttrRef with the full integer interface.

IntAttrRef()

Path nu.context.IntAttrRef. Kind Ref, sort ref, cardinality scalar.

Inherited methods

From nu.context.attrs.refs.AttrRef:

Call	Builds	Meaning
`.exists()`	`AttrExists`	A Query yielding whether this Ref's address is bound in `ctx.attrs`.

From nu.forms.primitives.int_.Int:

Call	Builds	Meaning
`a + b`	`Int \| Float`	Sum of self and other.
`a - b`	`Int \| Float`	Self minus other.
`a * b`	`Int \| Float`	Product of self and other.
`a / b`	`Float`	Self divided by other.
`a // b`	`Int \| Float`	Self floor-divided by other.
`a % b`	`Int \| Float`	Self modulo other.
`a ** b`	`Int \| Float`	Self raised to the other power.
`-a`	`Int`	Negation of self.
`+a`	`Int`	Self unchanged.
`abs(a)`	`Int`	Absolute value of self.
`a > b`	`Bool`	Self strictly greater than other.
`a < b`	`Bool`	Self strictly less than other.
`a >= b`	`Bool`	Self greater than or equal to other.
`a <= b`	`Bool`	Self less than or equal to other.
`a == b`	`Bool`	Self equal to other by value.
`a != b`	`Bool`	Self not equal to other by value.
`.is_(other)`	`Bool`	Identity comparison: self is other.
`.and_(other)`	`Bool`	Logical AND of self and other.
`.or_(other)`	`Bool`	Logical OR of self and other.
`.not_()`	`Bool`	Logical NOT of self.
`.bool_()`	`Bool`	Cast self to Bool.
`.bitand(other)`	`Int`	Bitwise AND: self & other.
`.bitor(other)`	`Int`	Bitwise OR: self \| other.
`a ^ b`	`Int`	Bitwise XOR: self ^ other.
`.bitnot()`	`Int`	Bitwise NOT: ~self.
`a << b`	`Int`	Left shift: self shifted left by other bits.
`a >> b`	`Int`	Right shift: self shifted right by other bits.

From nu.lang.forms.Form:

Call	Builds	Meaning
`.is_empty()`	`Bool`	True if this Form yields the EMPTY sentinel.
`.is_invalid()`	`Bool`	True if this Form yields the INVALID sentinel.
`.is_sentinel()`	`Bool`	True if this Form yields either sentinel (EMPTY or INVALID).
`.not_empty()`	`Bool`	True if this Form does not yield EMPTY.
`.not_invalid()`	`Bool`	True if this Form does not yield INVALID.

Undocumented: example.

ListAttrRef

An AttrRef with the full list interface.

ListAttrRef()

Path nu.context.ListAttrRef. Kind Ref, sort ref, cardinality scalar.

Inherited methods

From nu.context.attrs.refs.AttrRef:

Call	Builds	Meaning
`.exists()`	`AttrExists`	A Query yielding whether this Ref's address is bound in `ctx.attrs`.

From nu.forms.collections.list_.List:

Call	Builds	Meaning
`ListAttrRef.create()`	`List[T]`	Yield a fresh empty list.
`ListAttrRef.of(items)`	`List`	Yield a list from positional item expressions.
`a[key]`		Element at an int index, or subsequence for a slice.
`a + b`	`List[T]`	Concatenation of self and other.
`a * b`	`List[T]`	Self repeated n times.
`a[key] = value`	`Any`	Subscript write: self[index] = value.
`a > b`	`Bool`	Self strictly greater than other, element-by-element.
`a < b`	`Bool`	Self strictly less than other, element-by-element.
`a >= b`	`Bool`	Self greater than or equal to other, element-by-element.
`a <= b`	`Bool`	Self less than or equal to other, element-by-element.
`a == b`	`Bool`	Self equal to other by value.
`a != b`	`Bool`	Self not equal to other by value.
`.is_(other)`	`Bool`	Identity comparison: self is other.

From nu.forms.collections.abc.sequence.MutableSequenceForm:

Call	Builds	Meaning
`.append(value)`	`Any`	Append value to the end of self.
`.extend(other)`	`Any`	Extend self with the elements of other, in order.
`.insert(index, value)`	`Any`	Insert value at index, shifting later elements right.
`.pop(index=-1)`	`ElementResultT`	Remove and return the element at index.
`.del_at(index)`	`Any`	Remove the element at index.
`.remove(value)`	`Any`	Remove the first occurrence of value.
`.reverse()`	`Any`	Reverse self in place.
`.sort()`	`Any`	Sort self in place, ascending, using the elements' natural order.
`.copy()`	`CollectionResultT`	Shallow copy of self: a new sequence with the same elements.
`.clear()`	`Any`	Remove every element from self.

From nu.forms.collections.abc.sequence.SequenceForm:

Call	Builds	Meaning
`.first_elem()`	`ElementResultT`	First element of self.
`.last_elem()`	`ElementResultT`	Last element of self.
`.index(value)`	`Int`	Lowest index in self where value is found, searching from the left.
`.count(value)`	`Int`	Count of occurrences of value in self.
`.reversed()`	`CollectionResultT`	Self walked back to front, as a stream.

From nu.forms.collections.abc.collection.CollectionForm:

Call	Builds	Meaning
`.extract()`	`object`	Materialise the full subtree rooted at self.

From nu.forms.collections.abc.sized.SizedForm:

Call	Builds	Meaning
`.len()`	`Int`	Length of self.

From nu.forms.collections.abc.iterable.IterableForm:

Call	Builds	Meaning
`iter(a)`	`Iterator[ElementT]`	Open self into a lazy iterator stream (Python's `iter`).

From nu.forms.collections.abc.container.ContainerForm:

Call	Builds	Meaning
`.contains(item)`	`Bool`	Whether item is a member of self.

From nu.forms.collections.abc.sliceable.SliceableForm:

Call	Builds	Meaning
`.slice(start, stop, step=None)`	`ResultT`	Slice of self from start to stop, stepping by step.

From nu.lang.forms.Form:

Call	Builds	Meaning
`.is_empty()`	`Bool`	True if this Form yields the EMPTY sentinel.
`.is_invalid()`	`Bool`	True if this Form yields the INVALID sentinel.
`.is_sentinel()`	`Bool`	True if this Form yields either sentinel (EMPTY or INVALID).
`.not_empty()`	`Bool`	True if this Form does not yield EMPTY.
`.not_invalid()`	`Bool`	True if this Form does not yield INVALID.

Undocumented: example.

NoneAttrRef

An AttrRef with the none interface.

NoneAttrRef(source=None)

Path nu.context.NoneAttrRef. Kind Ref, sort ref, cardinality scalar.

Inherited methods

From nu.context.attrs.refs.AttrRef:

Call	Builds	Meaning
`.exists()`	`AttrExists`	A Query yielding whether this Ref's address is bound in `ctx.attrs`.

From nu.forms.primitives.none_.None_:

Call	Builds	Meaning
`.and_(other)`	`Bool`	Logical AND of self and other.
`.or_(other)`	`Bool`	Logical OR of self and other.
`.not_()`	`Bool`	Logical NOT of self.
`.bool_()`	`Bool`	Cast self to Bool.

From nu.lang.forms.Form:

Call	Builds	Meaning
`.is_empty()`	`Bool`	True if this Form yields the EMPTY sentinel.
`.is_invalid()`	`Bool`	True if this Form yields the INVALID sentinel.
`.is_sentinel()`	`Bool`	True if this Form yields either sentinel (EMPTY or INVALID).
`.not_empty()`	`Bool`	True if this Form does not yield EMPTY.
`.not_invalid()`	`Bool`	True if this Form does not yield INVALID.

Undocumented: example.

SetAttrRef

An AttrRef with the full set interface.

SetAttrRef()

Path nu.context.SetAttrRef. Kind Ref, sort ref, cardinality scalar.

Inherited methods

From nu.context.attrs.refs.AttrRef:

Call	Builds	Meaning
`.exists()`	`AttrExists`	A Query yielding whether this Ref's address is bound in `ctx.attrs`.

From nu.forms.collections.set_.Set:

Call	Builds	Meaning
`SetAttrRef.create()`	`Set[T]`	Build a fresh empty set.
`SetAttrRef.of(*items)`	`Set`	Build a set from positional item expressions.
`a > b`	`Bool`	Self is a proper superset of other.
`a < b`	`Bool`	Self is a proper subset of other.
`a >= b`	`Bool`	Self is a superset of other, or equal.
`a <= b`	`Bool`	Self is a subset of other, or equal.
`a == b`	`Bool`	Self equal to other by value.
`a != b`	`Bool`	Self not equal to other by value.
`.is_(other)`	`Bool`	Identity comparison: self is other.

From nu.forms.collections.abc.set_.MutableSetForm:

Call	Builds	Meaning
`.add(value)`	`Any`	Add value to self.
`.remove(value)`	`Any`	Remove value from self.
`.discard(value)`	`Any`	Remove value from self if present.
`.pop()`	`ElementResultT`	Remove and return an arbitrary element from self.
`.clear()`	`Any`	Remove every element from self.
`.update(other)`	`Any`	Add every element of other to self.
`.intersection_update(other)`	`Any`	Keep only the elements of self also found in other.
`.difference_update(other)`	`Any`	Remove every element of other from self.
`.symmetric_difference_update(other)`	`Any`	Keep the elements in exactly one of self and other.

From nu.forms.collections.abc.set_.SetLikeForm:

Call	Builds	Meaning
`.union(other)`	`CollectionResultT`	Union of self and other.
`.intersection(other)`	`CollectionResultT`	Intersection of self and other.
`.difference(other)`	`CollectionResultT`	Elements of self that are not in other.
`.symmetric_difference(other)`	`CollectionResultT`	Elements in exactly one of self and other, not both.
`.issubset(other)`	`Bool`	Whether every element of self is in other.
`.issuperset(other)`	`Bool`	Whether every element of other is in self.
`.isdisjoint(other)`	`Bool`	Whether self and other share no elements.
`.copy()`	`CollectionResultT`	Shallow copy of self.
`a \| b`	`CollectionResultT`	Union: self \| other.
`a & b`	`CollectionResultT`	Intersection: self & other.
`a - b`	`CollectionResultT`	Difference: self - other.
`a ^ b`	`CollectionResultT`	Symmetric difference: self ^ other.

From nu.forms.collections.abc.collection.CollectionForm:

Call	Builds	Meaning
`.extract()`	`object`	Materialise the full subtree rooted at self.

From nu.forms.collections.abc.sized.SizedForm:

Call	Builds	Meaning
`.len()`	`Int`	Length of self.

From nu.forms.collections.abc.iterable.IterableForm:

Call	Builds	Meaning
`iter(a)`	`Iterator[ElementT]`	Open self into a lazy iterator stream (Python's `iter`).

From nu.forms.collections.abc.container.ContainerForm:

Call	Builds	Meaning
`.contains(item)`	`Bool`	Whether item is a member of self.

From nu.lang.forms.Form:

Call	Builds	Meaning
`.is_empty()`	`Bool`	True if this Form yields the EMPTY sentinel.
`.is_invalid()`	`Bool`	True if this Form yields the INVALID sentinel.
`.is_sentinel()`	`Bool`	True if this Form yields either sentinel (EMPTY or INVALID).
`.not_empty()`	`Bool`	True if this Form does not yield EMPTY.
`.not_invalid()`	`Bool`	True if this Form does not yield INVALID.

Undocumented: example.

StrAttrRef

An AttrRef with the full string interface.

StrAttrRef()

Path nu.context.StrAttrRef. Kind Ref, sort ref, cardinality scalar.

Inherited methods

From nu.context.attrs.refs.AttrRef:

Call	Builds	Meaning
`.exists()`	`AttrExists`	A Query yielding whether this Ref's address is bound in `ctx.attrs`.

From nu.forms.primitives.str_.Str:

Call	Builds	Meaning
`a + b`	`Str`	Concatenation of self and other.
`a[key]`	`Str`	Character at an int index, or substring for a slice.
`a > b`	`Bool`	Self strictly greater than other, lexicographically.
`a < b`	`Bool`	Self strictly less than other, lexicographically.
`a >= b`	`Bool`	Self greater than or equal to other, lexicographically.
`a <= b`	`Bool`	Self less than or equal to other, lexicographically.
`a == b`	`Bool`	Self equal to other by value.
`a != b`	`Bool`	Self not equal to other by value.
`.is_(other)`	`Bool`	Identity comparison: self is other.
`.and_(other)`	`Bool`	Logical AND of self and other.
`.or_(other)`	`Bool`	Logical OR of self and other.
`.not_()`	`Bool`	Logical NOT of self.
`.bool_()`	`Bool`	Cast self to Bool.
`.upper()`	`Str`	Self converted to uppercase.
`.lower()`	`Str`	Self converted to lowercase.
`.title()`	`Str`	Self converted to title case.
`.capitalize()`	`Str`	Self with only the first character capitalized.
`.swapcase()`	`Str`	Self with uppercase and lowercase characters swapped.
`.casefold()`	`Str`	Self folded for aggressive, caseless matching.
`.strip(chars=None)`	`Str`	Self with leading and trailing characters removed.
`.lstrip(chars=None)`	`Str`	Self with leading characters removed.
`.rstrip(chars=None)`	`Str`	Self with trailing characters removed.
`.split(sep=None, maxsplit=-1)`	`List`	Self split into a list on sep, from the left.
`.rsplit(sep=None, maxsplit=-1)`	`List`	Self split into a list on sep, from the right.
`.splitlines(keepends=False)`	`List`	Self split into a list at line boundaries.
`.partition(sep)`	`Tuple`	Self split around the first occurrence of sep into a 3-tuple.
`.rpartition(sep)`	`Tuple`	Self split around the last occurrence of sep into a 3-tuple.
`.find(sub, start=0, end=None)`	`Int`	Lowest index in self where sub is found, searching from the left.
`.rfind(sub, start=0, end=None)`	`Int`	Highest index in self where sub is found, searching from the right.
`.index(sub, start=0, end=None)`	`Int`	Lowest index in self where sub is found, searching from the left.
`.rindex(sub, start=0, end=None)`	`Int`	Highest index in self where sub is found, searching from the right.
`.count_substring(sub)`	`Int`	Count of non-overlapping occurrences of sub in self.
`.startswith(prefix)`	`Bool`	Whether self starts with prefix.
`.endswith(suffix)`	`Bool`	Whether self ends with suffix.
`.isdigit()`	`Bool`	Whether every character in self is a digit.
`.isalpha()`	`Bool`	Whether every character in self is alphabetic.
`.isalnum()`	`Bool`	Whether every character in self is alphanumeric.
`.isspace()`	`Bool`	Whether every character in self is whitespace.
`.isnumeric()`	`Bool`	Whether every character in self is numeric.
`.isdecimal()`	`Bool`	Whether every character in self is a decimal character.
`.isidentifier()`	`Bool`	Whether self is a valid Python identifier.
`.isprintable()`	`Bool`	Whether every character in self is printable.
`.istitle()`	`Bool`	Whether self is titlecased.
`.isupper()`	`Bool`	Whether every cased character in self is uppercase.
`.islower()`	`Bool`	Whether every cased character in self is lowercase.
`.isascii()`	`Bool`	Whether every character in self is ASCII.
`.center(width, fillchar=' ')`	`Str`	Self centered in a field of the given width.
`.ljust(width, fillchar=' ')`	`Str`	Self left-justified in a field of the given width.
`.rjust(width, fillchar=' ')`	`Str`	Self right-justified in a field of the given width.
`.zfill(width)`	`Str`	Self padded with leading zeros to the given width.
`.expandtabs(tabsize=8)`	`Str`	Self with tab characters expanded to spaces.
`.replace(old, new, count=-1)`	`Str`	Self with occurrences of old replaced by new.
`.removeprefix(prefix)`	`Str`	Self with the given prefix removed if present.
`.removesuffix(suffix)`	`Str`	Self with the given suffix removed if present.
`.translate(table)`	`Str`	Self with characters mapped through a translation table.
`.format_map(mapping)`	`Str`	Self formatted with `{field}` placeholders filled from mapping.
`.encode(encoding='utf-8')`	`Bytes`	Self encoded to Bytes.
`.join(iterable)`	`Str`	Elements of iterable joined together with self as separator.

From nu.lang.forms.Form:

Call	Builds	Meaning
`.is_empty()`	`Bool`	True if this Form yields the EMPTY sentinel.
`.is_invalid()`	`Bool`	True if this Form yields the INVALID sentinel.
`.is_sentinel()`	`Bool`	True if this Form yields either sentinel (EMPTY or INVALID).
`.not_empty()`	`Bool`	True if this Form does not yield EMPTY.
`.not_invalid()`	`Bool`	True if this Form does not yield INVALID.

Undocumented: example.

TupleAttrRef

An AttrRef with the full tuple interface.

TupleAttrRef()

Path nu.context.TupleAttrRef. Kind Ref, sort ref, cardinality scalar.

Inherited methods

From nu.context.attrs.refs.AttrRef:

Call	Builds	Meaning
`.exists()`	`AttrExists`	A Query yielding whether this Ref's address is bound in `ctx.attrs`.

From nu.forms.collections.tuple_.Tuple:

Call	Builds	Meaning
`TupleAttrRef.create()`	`Tuple[Unpack[Ts]]`	Empty tuple.
`TupleAttrRef.of(items)`	`Tuple`	Tuple built from positional item expressions.
`a + b`	`Tuple`	Concatenation of self and other.
`a * b`	`Tuple`	Self repeated n times.
`a > b`	`Bool`	Self strictly greater than other, lexicographically.
`a < b`	`Bool`	Self strictly less than other, lexicographically.
`a >= b`	`Bool`	Self greater than or equal to other, lexicographically.
`a <= b`	`Bool`	Self less than or equal to other, lexicographically.
`a == b`	`Bool`	Self equal to other by value.
`a != b`	`Bool`	Self not equal to other by value.
`.is_(other)`	`Bool`	Identity comparison: self is other.

From nu.forms.collections.abc.sequence.SequenceForm:

Call	Builds	Meaning
`a[key]`	`ElementResultT \| CollectionResultT`	Element at an int index, or subsequence for a slice.
`.first_elem()`	`ElementResultT`	First element of self.
`.last_elem()`	`ElementResultT`	Last element of self.
`.index(value)`	`Int`	Lowest index in self where value is found, searching from the left.
`.count(value)`	`Int`	Count of occurrences of value in self.
`.reversed()`	`CollectionResultT`	Self walked back to front, as a stream.

From nu.forms.collections.abc.collection.CollectionForm:

Call	Builds	Meaning
`.extract()`	`object`	Materialise the full subtree rooted at self.

From nu.forms.collections.abc.sized.SizedForm:

Call	Builds	Meaning
`.len()`	`Int`	Length of self.

From nu.forms.collections.abc.iterable.IterableForm:

Call	Builds	Meaning
`iter(a)`	`Iterator[ElementT]`	Open self into a lazy iterator stream (Python's `iter`).

From nu.forms.collections.abc.container.ContainerForm:

Call	Builds	Meaning
`.contains(item)`	`Bool`	Whether item is a member of self.

From nu.forms.collections.abc.sliceable.SliceableForm:

Call	Builds	Meaning
`.slice(start, stop, step=None)`	`ResultT`	Slice of self from start to stop, stepping by step.

From nu.lang.forms.Form:

Call	Builds	Meaning
`.is_empty()`	`Bool`	True if this Form yields the EMPTY sentinel.
`.is_invalid()`	`Bool`	True if this Form yields the INVALID sentinel.
`.is_sentinel()`	`Bool`	True if this Form yields either sentinel (EMPTY or INVALID).
`.not_empty()`	`Bool`	True if this Form does not yield EMPTY.
`.not_invalid()`	`Bool`	True if this Form does not yield INVALID.

Undocumented: example.

attrs.refs

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