collections.views

Module nu.forms.collections.views.

Dict view interfaces - DictKeys, DictValues, DictItems.

Name	Sort	Call	Meaning
DictItems	`scalar_query`	`DictItems()`	View of a Dict's `(key, value)` pairs, produced by `dict.items()`.
DictKeys	`scalar_query`	`DictKeys()`	View of a Dict's keys, produced by `dict.keys()`.
DictValues	`scalar_query`	`DictValues()`	View of a Dict's values, produced by `dict.values()`.

DictItems

View of a Dict's (key, value) pairs, produced by dict.items().

DictItems()

Path nu.forms.DictItems. Kind ScalarQuery, sort scalar_query, cardinality scalar.

Notes

Set-like: union, intersection, difference, issubset, and the | & - ^ operators all work on it directly, matching Python's dict.items() when the values are hashable.
Lazy and live: it holds no items of its own, it re-reads the backing Dict on every evaluation. Mutate the Dict and the view reflects it on the next nu.run.
Iterable, sized (len()), and supports contains with a (key, value) tuple.

Example

items = nu.Dict({"a": 1, "b": 2}).items()
nu.run(items.len())[0]
nu.run(items.contains(("a", 1)))[0]

2
True

Methods

`.to_list()`

Snapshot the items into a List.

Builds List[tuple[K, V]].

Yields

The (key, value) pairs as a plain List, in dict iteration order. Unlike the view itself, the result no longer tracks the backing Dict.

Example

nu.run(nu.Dict({"a": 1, "b": 2}).items().to_list())[0]

[('a', 1), ('b', 2)]

`.to_set()`

Snapshot the items into a Set.

Builds Set[tuple[K, V]].

Yields

The (key, value) pairs as a plain Set. Unlike the view itself, the result no longer tracks the backing Dict.

Notes

Raises at evaluation time if any value is unhashable.

Example

nu.run(nu.Dict({"a": 1, "b": 2}).items().to_set())[0] == {("a", 1), ("b", 2)}

True

Inherited methods

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.

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()`	`Iterator[ElementT]`	Open self into a lazy iterator stream over its elements.

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
`a == b`	`Bool`	Self equal to other by value: an `Eq` term, never a Python bool.
`a != b`	`Bool`	Self not equal to other by value: a `Ne` term, never a Python bool.
`.is_empty()`	`Bool`	True if this Form yields the EMPTY sentinel.
`.not_empty()`	`Bool`	True if this Form does not yield EMPTY.
`.fallback(*alternatives)`	`Self`	The first of this value and `alternatives` that is not EMPTY.

DictKeys

View of a Dict's keys, produced by dict.keys().

DictKeys()

Path nu.forms.DictKeys. Kind ScalarQuery, sort scalar_query, cardinality scalar.

Notes

Set-like: union, intersection, difference, issubset, and the | & - ^ operators all work on it directly, matching Python's dict.keys().
Lazy and live: it holds no keys of its own, it re-reads the backing Dict on every evaluation. Mutate the Dict and the view reflects it on the next nu.run.
Iterable, sized (len()), and supports contains.

Example

keys = nu.Dict({"a": 1, "b": 2}).keys()
nu.run(keys.len())[0]
nu.run(keys.contains("a"))[0]

2
True

Methods

`.to_list()`

Snapshot the keys into a List.

Builds List[K].

Yields

The keys as a plain List, in dict iteration order. Unlike the view itself, the result no longer tracks the backing Dict.

Example

nu.run(nu.Dict({"a": 1, "b": 2}).keys().to_list())[0]

['a', 'b']

`.to_set()`

Snapshot the keys into a Set.

Builds Set[K].

Yields

The keys as a plain Set. Unlike the view itself, the result no longer tracks the backing Dict.

Example

nu.run(nu.Dict({"a": 1, "b": 2}).keys().to_set())[0] == {"a", "b"}

True

Inherited methods

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.

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()`	`Iterator[ElementT]`	Open self into a lazy iterator stream over its elements.

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
`a == b`	`Bool`	Self equal to other by value: an `Eq` term, never a Python bool.
`a != b`	`Bool`	Self not equal to other by value: a `Ne` term, never a Python bool.
`.is_empty()`	`Bool`	True if this Form yields the EMPTY sentinel.
`.not_empty()`	`Bool`	True if this Form does not yield EMPTY.
`.fallback(*alternatives)`	`Self`	The first of this value and `alternatives` that is not EMPTY.

DictValues

View of a Dict's values, produced by dict.values().

DictValues()

Path nu.forms.DictValues. Kind ScalarQuery, sort scalar_query, cardinality scalar.

Notes

Not set-like: values can repeat and aren't required to be hashable, so there's no union/intersection here, unlike DictKeys and DictItems. Just Collection: iterable, sized (len()), and contains.
Lazy and live: it holds no values of its own, it re-reads the backing Dict on every evaluation. Mutate the Dict and the view reflects it on the next nu.run.
No == / !=: Python compares values views by identity, never by content, so both raise. Compare a snapshot instead: values.to_list() == [...].

Example

values = nu.Dict({"a": 1, "b": 2}).values()
nu.run(values.len())[0]
nu.run(values.contains(1))[0]

2
True

Methods

`.to_list()`

Snapshot the values into a List.

Builds List[V].

Yields

The values as a plain List, in dict iteration order. Unlike the view itself, the result no longer tracks the backing Dict.

Example

nu.run(nu.Dict({"a": 1, "b": 2}).values().to_list())[0]

[1, 2]

`.to_set()`

Snapshot the values into a Set.

Builds Set[V].

Yields

The values as a plain Set. Unlike the view itself, the result no longer tracks the backing Dict.

Notes

Raises at evaluation time if any value is unhashable.

Example

nu.run(nu.Dict({"a": 1, "b": 2}).values().to_set())[0] == {1, 2}

True

Inherited methods

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()`	`Iterator[ElementT]`	Open self into a lazy iterator stream over its elements.

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.
`.not_empty()`	`Bool`	True if this Form does not yield EMPTY.
`.fallback(*alternatives)`	`Self`	The first of this value and `alternatives` that is not EMPTY.

collections.views

On this page