1:- module(canny_arch,
    2          [ current_arch/1,
    3            current_arch_os/2,
    4            current_os/1
    5          ]).

 current_arch(?Arch:pair) is semidet

Unifies Arch with the current host's architecture and operating system. Usefully reads the pair as a Prolog term with which you can unify its component parts.

The Prolog arch flag combines both the architecture and the operating system as a dash-separated pair. The predicate splits these two components apart by reading the underlying atom as a Prolog term. This makes an assumption about the format of the arch flag.

   19current_arch(Arch) :-
   20    current_prolog_flag(arch, Arch0),
   21    atom_to_term(Arch0, Arch, []).

 current_arch_os(?Arch, ?OS) is semidet

Unifies OS with the current operating system. Splits the host architecture into its two components: the bit-wise sub-architecture and the operating system. Operating system is one of: win32 or win64 for Windows, darwin for macOS, or linux for Linux. Maps architecture bit-width to an atomic Arch token for contemporary 64-bit hosts, one of: x64, x86_64. Darwin and Linux report the latter, Windows the former.

   33current_arch_os(Arch, OS) :- current_arch(Arch-OS).

 current_os(?OS) is semidet

Succeeds for current OS, one of:

• win32
• win64
• darwin
• linux

   44current_os(OS) :- current_arch_os(_, OS)