{ debug, integer, intrinsics, list, set, string, type, ... }:
  let
    ExecutableFormat#: Enum { elf, macho, pe, unknown, wasm }
    =   type.enum "ExecutableFormat"
        {
          elf                           =   1;
          macho                         =   2;
          pe                            =   3;
          unknown                       =   4;
          wasm                          =   5;
        };

    Family                              =   null;# || { parent = Family; };

    Kernel# struct { executableFormat: ExecutableFormat, family: Family }
    =   type "Kernel"
        {
          inherit ExecutableFormat Family;
          inherit all families;

          isDarwin#: System -> bool
          =   { kernel, ... } @ self:
                kernel == all.darwin;

          isLinux#: System -> bool
          =   { kernel, ... } @ self:
                kernel == all.linux;

          from#: type -> (string | Kernel)? -> Kernel
          =   kernel:
                if !(Kernel.isInstanceOf kernel)
                then
                  type.matchPrimitiveOrPanic kernel
                  {
                    null                =   all.none;
                    string              =   all.${kernel} or (debug.panic "Kernel" "Unknown kernel »${kernel}«!");
                  }
                else
                  kernel;
        };

    families#: { string -> Family }
    =   {
          bsd                           =   { parent = families.unix; };
          darwin                        =   { parent = families.bsd;  };
          linux                         =   { parent = families.unix; };
          none                          =   { parent = null;          };
          unix                          =   { parent = families.none; };
          windows                       =   { parent = families.none; };
        };

    all#: { string -> Kernel }
    =   let
          new#: ExecutableFormat -> Family -> Kernel
          =   executableFormat:
              family:
                Kernel.instanciate
                {
                  __toString            =   { name, ... }: name;
                  inherit executableFormat family;
                };

          all
          =   {
                cygwin                  =   new ExecutableFormat.elf      families.linux;
                darwin                  =   new ExecutableFormat.macho    families.darwin;
                freebsd                 =   new ExecutableFormat.elf      families.bsd;
                ios                     =   new ExecutableFormat.macho    families.darwin;
                linux                   =   new ExecutableFormat.elf      families.linux;
                ghcjs                   =   new ExecutableFormat.unknown  families.none;
                genode                  =   new ExecutableFormat.elf      families.none;
                macos                   =   all.darwin;
                mmixware                =   new ExecutableFormat.unknown  families.none;
                netbsd                  =   new ExecutableFormat.elf      families.bsd;
                none                    =   new ExecutableFormat.unknown  families.none;
                openbsd                 =   new ExecutableFormat.elf      families.bsd;
                redox                   =   new ExecutableFormat.elf      families.none;
                solaris                 =   new ExecutableFormat.elf      families.unix;
                tvos                    =   all.ios;
                wasi                    =   new ExecutableFormat.wasm     families.none;
                watchos                 =   all.ios;
                win32                   =   all.windows;
                win64                   =   all.windows;
                windows                 =   new ExecutableFormat.pe       families.windows;
              };
        in
          set.name all;
  in
    Kernel