(1) show contents of file "fac.txt":
======================================================================

$ cat fac.txt



	fac(n) {
		f = 1;
		while (n > 1) {
			f = f*n;
			n = n - 1;
		}
		return(f);
	}

	print fac(4);


(2) interpret & compile file "fac.txt"
======================================================================

$ cat fac.txt | pl -s interp.pl -g doit

	%  library(assoc) compiled into assoc 0.00 sec, 11,784 bytes
	% interp.pl compiled 0.01 sec, 47,152 bytes
	|: |:

	tokens:

	[id(fac), (, id(n), ), {, id(f), =, num(1), (;), while, (, id(n), rop(>), num(1), ), {, id(f), =, id(f), mop(*), id(n), (;), id(n), =, id(n), aop(-), num(1), (;), }, return, (, id(f), ), (;), }, print, id(fac), (, num(4), ), (;)]

	AST:

	sequence(function(fac, n, sequence(assign(f, n(1)), sequence(while(bin(>, v(n), n(1)), sequence(assign(f, bin(*, v(f), v(n))), assign(n, bin(-, v(n), n(1))))), return(v(f))))), print(call(fac, n(4))))


	VM code:

	 0:     jmp 33
	 2:     alloc 1
	 4:     pushc 1
	 6:     pop 1
	 8:     pushv 0
	10:     pushc 1
	12:     jle 30
	14:     pushv 1
	16:     pushv 0
	18:     mul
	19:     pop 1
	21:     pushv 0
	23:     pushc 1
	25:     sub
	26:     pop 0
	28:     jmp 8
	30:     pushv 1
	32:     ret
	33:     pushc 4
	35:     call 2
	37:     print
	38:     halt

	intcode:

	[9, 33, 1, 1, 2, 1, 4, 1, 3, 0, 2, 1, 12, 30, 3, 1, 3, 0, 7, 4, 1, 3, 0, 2, 1, 6, 4, 0, 9, 8, 3, 1, 15, 2, 4, 13, 2, 14, 0]

	program output:

	24

	% halt


(3) feed generated integer code to VM implementation in Haskell
======================================================================
$ hugs vm.hs


	Main> main
	[9, 33, 1, 1, 2, 1, 4, 1, 3, 0, 2, 1, 12, 30, 3, 1, 3, 0, 7, 4, 1, 3, 0, 2, 1, 6, 4, 0, 9, 8, 3, 1, 15, 2, 4, 13, 2, 14, 0]
	24


(4) extract integers
======================================================================

        $ echo "[9, 33, 1, 1, 2, 1, 4, 1, 3, 0, 2, 1, 12, 30, 3, 1, 3, 0, 7, 4, 1, 3, 0, 2, 1, 6, 4, 0, 9, 8, 3, 1, 15, 2, 4, 13, 2, 14, 0]" | tr -d ",[]"

        9 33 1 1 2 1 4 1 3 0 2 1 12 30 3 1 3 0 7 4 1 3 0 2 1 6 4 0 9 8 3 1 15 2 4 13 2 14 0


(5) feed integer code to VM implementation in J
======================================================================

        $ (echo "instrs =: 9 33 1 1 2 1 4 1 3 0 2 1 12 30 3 1 3 0 7 4 1 3 0 2 1 6 4 0 9 8 3 1 15 2 4 13 2 14 0"; cat vm.ijs) | ~/j601/jconsole

                         24