@hackage stm-containers1.2.0.3

This library is based on an STM-specialized implementation of Hash Array Mapped Trie. It provides efficient implementations of Map, Set and other data structures, which starting from version 1 perform even better than their counterparts from "unordered-containers", but also scale well on concurrent access patterns. . For details on performance of the library, which are a bit outdated, see this blog post.