Module expr_pool 

Structs

ExprId

Handle to an expression in the symbolic world (spec §8.1). In-process hash-consing depends on creation order, so ExprId is forbidden from cross-process serialization/caching (ADR §6).

ExprPool

Process-wide shared hash-consing pool (spec §8.1/§12.4): maps content hash → ExprId. The central store is append-only (the symbolic layer is acyclic and resident), concurrency-safe.

Enums

ExprData

Node in the symbolic world (spec §8.1). Add/Mul are stored as canonically ordered n-ary lists (spec §8.4), so equality is ExprId equality (O(1)).