effects

Module nu.tree.effects.

Pre-compilation effect analysis over Term trees.

A tree walk that reads each node's declared mutation slots and yields the (Ref, Effect) edges of the subtree -- the same information the effect attribute (nu.lang.attributes.effects) synthesizes at compile time, but available before a Program exists. Rewrites that inject boundaries (Brackets, Policies) run pre-compile and need exactly this.

Folds on top of the walk: is_pure / reads / writes / fabrics and the fabric predicates touches_fabric / has_write_on_fabric.

fabrics

Fold the subtree's Refs to the set of fabric identities they touch.

tree.fabrics(node)

Path nu.tree.fabrics. Defined on nu.tree.effects, bound as a function. Builds frozenset[type].

A Ref's fabric identity is its type.

Arguments

Undocumented: example.

has_write_on_fabric

Predicate: subtree has a WRITE effect through a Ref of given type.

tree.has_write_on_fabric(node, ref_types)

Path nu.tree.has_write_on_fabric. Defined on nu.tree.effects, bound as a function. Builds bool.

Arguments

Undocumented: example.

is_pure

An atom or composition with no tracked effects is pure.

tree.is_pure(node)

Path nu.tree.is_pure. Defined on nu.tree.effects, bound as a function. Builds bool.

A subtree carrying a dynamic (Sort.DYNAMIC) node is never pure: the inner tree the carrier will produce is opaque at analysis time, so we treat the whole subtree as potentially effectful.

Arguments

Undocumented: example.

iter_effects

Walk the subtree yielding (ref_instance, effect) for every Ref child.

tree.iter_effects(node)

Path nu.tree.iter_effects. Defined on nu.tree.effects, bound as a function. Builds Iterator[tuple[Ref, Effect]].

Mirrors the effect synthesis (nu.lang.attributes.effects): a Ref child in a mutation slot (declared via mutates) binds as WRITE; a Ref child in a structural slot (declared via structural) binds as nothing - it is address structure, never evaluated; any other Ref child binds as READ. The recursion still descends every child, so value reads nested inside a structural subtree are collected. Pre-compilation tree walk -- no Program needed.

Arguments

Undocumented: example.

reads

Refs the subtree reads.

tree.reads(node)

Path nu.tree.reads. Defined on nu.tree.effects, bound as a function. Builds frozenset[Ref].

Arguments

Undocumented: example.

touches_fabric

Predicate: subtree holds at least one Ref whose type is in ref_types.

tree.touches_fabric(node, ref_types)

Path nu.tree.touches_fabric. Defined on nu.tree.effects, bound as a function. Builds bool.

Arguments

Undocumented: example.

writes

Refs the subtree writes.

tree.writes(node)

Path nu.tree.writes. Defined on nu.tree.effects, bound as a function. Builds frozenset[Ref].

Arguments

Undocumented: example.