Internal: atomically set a lazy value to locked (or return false if already memoized).

Internal: release an atomically memoized lazy value.

Internal: test if a lazy value is in whnf.

Internal: test if a heap allocated data type is thread-shared.

Internal: test if a heap allocated data type is unique.

Internal: test if a heap allocated lazy value is in whnf.

Internal: compress indirection chains.

Internal: explicitly force update-in-place for lazy values.

Internal: marker for lazy values that will be memoized (used to for correct reuse and reference counting).