# The intern package

[ Tags: bsd3, data, data-structures, library ] [ Propose Tags ]

Changes from 0.8 to 0.9

• Removed identity from the Interned class, to support applications where the identity is obtained by other means (e.g. a unique Ptr value)

Changes from 0.7 to 0.8

• Disabled cache removal as it was causing problems on large data sets. There is no good way to ensure that both references remain alive long enough to finish comparisons.

• Switched to IORef from MVar

Changes from 0.6 to 0.7

• Fixed problem where comparisons could happen between data structures while one was still a thunk, leading to equal structures comparing as inequal in limited circumstances, by appropriately using strictness annotations.

Efficient hash-consing for arbitrary data types

Changes from 0.5.2 to 0.6

• Widened the caches so they don't go through a single MVar per type. This has made a dramatic impact on performance. However, this broke the previous invariant that newer entries always had higher Ids than older entries.

Changes from 0.5.1 to 0.5.2