This is primarily a bug fix release. It has some new features: Syntactic sugar for writing nested attribute sets. Instead of { foo = { bar = 123; xyzzy = true; }; a = { b = { c = "d"; }; }; } you can write { foo.bar = 123; foo.xyzzy = true; a.b.c = "d"; } This is useful, for instance, in NixOS configuration files. Support for Nix channels generated by Hydra, the Nix-based continuous build system. (Hydra generates NAR archives on the fly, so the size and hash of these archives isn’t known in advance.) Support i686-linux builds directly on x86_64-linux Nix installations. This is implemented using the personality() syscall, which causes uname to return i686 in child processes. Various improvements to the chroot support. Building in a chroot works quite well now. Nix no longer blocks if it tries to build a path and another process is already building the same path. Instead it tries to build another buildable path first. This improves parallelism. Support for large (> 4 GiB) files in NAR archives. Various (performance) improvements to the remote build mechanism. New primops: builtins.addErrorContext (to add a string to stack traces — useful for debugging), builtins.isBool, builtins.isString, builtins.isInt, builtins.intersectAttrs. OpenSolaris support (Sander van der Burg). Stack traces are no longer displayed unless the --show-trace option is used. The scoping rules for inherit (e) ... in recursive attribute sets have changed. The expression e can now refer to the attributes defined in the containing set.