Attribute Macro topo_macro::bound

#[bound]

Transforms a function declaration into a topological function invoked with macro syntax to bind its call tree's (sub)topology to the parent topology.

A macro transformation is used to capture unique callsite information from the invoking function. In the current implementation, we synthesize a unique std::any::TypeId at each callsite which can be used to identify the chain of topological invocations.

Implications of using macros

Upside: Because topological function calls are a bit more expensive than normal function calls, it makes sense to call them out as different invocations than typical functions, in particular because they literally bind to the source location at which they're invoked.

However, it is not currently feasible to abstract over topological functions, visibility rules are less granular, autocomplete doesn't show types, and error messages are generally worse.

Macro alternatives

React: runtime-only tracking, forces hooks to only be used at the top-level

TODO explain more

Compose: uses nifty compiler transform on each callsite

TODO

Rust #[track_caller] attribute

Not yet implemented, not clear it'll offer same guarantees as chained TypeIds.

TODO expand