Nice! The whole implementation seems to be a bit over 1k lines. https://github.com/zig-wasm/zorth/blob/main/src/zorth.zig

The tests give some examples of what to try like: 65 EMIT

      const tests = .{
        .{ "65 EMIT ", "A" },
        .{ "777 65 EMIT ", "A" },
        .{ "32 DUP + 1+ EMIT ", "A" },
        .{ "16 DUP 2DUP + + + 1+ EMIT ", "A" },
        .{ "8 DUP * 1+ EMIT ", "A" },
        .{ "CHAR A EMIT ", "A" },
        .{ ": SLOW WORD FIND >CFA EXECUTE ; 65 SLOW EMIT ", "A" },
        .{ fmt.comptimePrint("{d} DSP@ 8 TELL ", .{s}), "SYSCALL0" },
        .{ fmt.comptimePrint("{d} DSP@ HERE @ 8 CMOVE HERE @ 8 TELL ", .{s}), "SYSCALL0" },
        .{ fmt.comptimePrint("{d} DSP@ 2 NUMBER DROP EMIT ", .{mem.readInt(u16, "65", .little)}), "A" },
        .{ "64 >R RSP@ 1 TELL RDROP ", "@" },
        .{ "64 DSP@ RSP@ SWAP C@C! RSP@ 1 TELL ", "@" },
        .{ "64 >R 1 RSP@ +! RSP@ 1 TELL ", "A" },
        .{
            \\: <BUILDS WORD CREATE DODOES , 0 , ;
            \\: DOES> R> LATEST @ >DFA ! ;
            \\: CONST <BUILDS , DOES> @ ;
            \\
            \\65 CONST FOO
            \\FOO EMIT 
            ,
            "A",
        },
        .{ preamble ++ "VERSION . ", "47 " },
        .{ preamble ++ "CR ", "\n" },
        .{ preamble ++ "0 1 > . 1 0 > . ", "0 -1 " },
        .{ preamble ++ "0 1 >= . 0 0 >= . ", "0 -1 " },
        .{ preamble ++ "0 0<> . 1 0<> . ", "0 -1 " },
        .{ preamble ++ "1 0<= . 0 0<= . ", "0 -1 " },
        .{ preamble ++ "-1 0>= . 0 0>= . ", "0 -1 " },
        .{ preamble ++ "0 0 OR . 0 -1 OR . ", "0 -1 " },
        .{ preamble ++ "-1 -1 XOR . 0 -1 XOR . ", "0 -1 " },
        .{ preamble ++ "-1 INVERT . 0 INVERT . ", "0 -1 " },
        .{ preamble ++ "3 4 5 .S ", "5 4 3 " },
        .{ preamble ++ "1 2 3 4 2SWAP .S ", "2 1 4 3 " },
        .{ preamble ++ "F_IMMED F_HIDDEN .S ", "32 128 " },
        .{ preamble ++ ": CFA@ WORD FIND >CFA @ ; CFA@ >DFA DOCOL = . ", "-1 " },
        .{ preamble ++ "3 4 5 WITHIN . ", "0 " },
        .{ preamble ++ fmt.comptimePrint(": GETPPID {d} SYSCALL0 ; GETPPID . ", .{@intFromEnum(syscalls.X64.getppid)}), p },
        .{ preamble ++ "ARGC . ", "2 " },
        .{ preamble ++ "ENVIRON @ DUP STRLEN TELL ", mem.sliceTo(os.environ[0], 0) },
        .{ preamble ++ "SEE >DFA ", ": >DFA >CFA 8+ EXIT ;\n" },
        .{ preamble ++ "SEE HIDE ", ": HIDE WORD FIND HIDDEN ;\n" },
        .{ preamble ++ "SEE QUIT ", ": QUIT R0 RSP! INTERPRET BRANCH ( -16 ) ;\n" },
        .{
            preamble ++
                \\: FOO THROW ;
                \\: TEST-EXCEPTIONS 25 ['] FOO CATCH ?DUP IF ." FOO threw exception: " . CR DROP THEN ;
                \\TEST-EXCEPTIONS 
            ,
            "FOO threw exception: 25 \n",
        },