• New best-fit allocator for the major heap
• Preliminary runtime work for OCaml multicore
• Immutable strings are now enforced at configuration time
• User-defined indexing operators for multidimensional arrays
• Coming soon: statmemprof, a new statistical memory profiler. The external API will be released next version.
• Various improvements to the manual
• More precise exhaustiveness check for GADTs
• Many bug fixes

See also the detailed list of changes