PEGO
A260: Typed List Slabs
Small typed list backing can share chunks instead of allocating a separate backing array for every list.
Mechanism and Invariants
After the first nonempty small-list bootstrap, list slabs start at 64 elements and grow to 1,024, satisfying requested lengths. Lists above the small-list policy use exact-size allocations. Published slices constrain capacity for append isolation; escaped slices retain their backing chunk. Empty-list nil/non-nil shapes remain exact.
Scope and State
Default generated Go typed direct and conversion output. Node child slabs and TypeScript arrays are separate policies.
Reference Control
Private disableTypedListSlabs emits independent list arrays; object slab
policy remains separately selectable. Bootstrap disable changes early
allocation, not all list slabs.
Evidence and Implementation
Records 074/098 document first-chunk/bootstrap changes and retained-output fixtures. The list control helps attribute sibling retention but does not establish lower retained memory for every result or universal throughput gains.
Evidence records: 048, 074, 098.
Source owners: astSlice generation,
disableTypedListSlabs, slices/individual controls.
The comparison policy distinguishes same-source controls, historical changes and full checkpoints.