# Prerequisites

- GNU Autoconf (https://www.gnu.org/software/autoconf/) and the autoconf-archive macro collection (https://www.gnu.org/software/autoconf-archive/). These are needed to run the bootstrap script.

- GNU Make.

- Bash Shell. The `./configure` script relies on bashisms, so Bash is required.

- A version of GCC or Clang that supports C++17.

- `pkg-config` to locate dependencies. If your distribution does not provide it, you can get it from http://www.freedesktop.org/wiki/Software/pkg-config.

- The OpenSSL library to calculate cryptographic hashes. If your distribution does not provide it, you can get it from https://www.openssl.org.

- The `libbrotlienc` and `libbrotlidec` libraries to provide implementation of the Brotli compression algorithm. They are available for download from the official repository https://github.com/google/brotli.

- cURL and its library. If your distribution does not provide it, you can get it from https://curl.haxx.se/.

- The SQLite embedded database library, version 3.6.19 or higher. If your distribution does not provide it, please install it from http://www.sqlite.org/.

- The Boehm garbage collector to reduce the evaluator’s memory consumption (optional). To enable it, install `pkgconfig` and the Boehm garbage collector, and pass the flag `--enable-gc` to `configure`.

- The `boost` library of version 1.66.0 or higher. It can be obtained from the official web site https://www.boost.org/.

- The `editline` library of version 1.14.0 or higher. It can be obtained from the its repository https://github.com/troglobit/editline.

- The `libsodium` library for verifying cryptographic signatures of contents fetched from binary caches. It can be obtained from the official web site https://libsodium.org.

- Recent versions of Bison and Flex to build the parser. (This is because Nix needs GLR support in Bison and reentrancy support in Flex.) For Bison, you need version 2.6, which can be obtained from the GNU FTP server. For Flex, you need version 2.5.35, which is available on SourceForge. Slightly older versions may also work, but ancient versions like the ubiquitous 2.5.4a won't.

- The `libseccomp` is used to provide syscall filtering on Linux. This is an optional dependency and can be disabled passing a `--disable-seccomp-sandboxing` option to the `configure` script (Not recommended unless your system doesn't support `libseccomp`). To get the library, visit https://github.com/seccomp/libseccomp.

- On 64-bit x86 machines only, `libcpuid` library is used to determine which microarchitecture levels are supported (e.g., as whether to have `x86_64-v2-linux` among additional system types). The library is available from its homepage http://libcpuid.sourceforge.net. This is an optional dependency and can be disabled by providing a `--disable-cpuid` to the `configure` script.