// growing the language from inside a program, while it compiles

// x |> f calls f(x). on a stack machine that's just "call": the value is
// already on the stack, under f's address.
immediate fn pipe_op() { next(); add_binop("|>", 1, "c"); return 0; }
pipe_op

// unless (c) stmt
immediate fn unless() {
	let a;
	next(); expect(intern("(")); plainuse(expr()); rval(); expect(intern(")"));
	emitseq(useq[0], ulen[0]);		// not
	a = hole(); op(O_JZ);
	substmt();
	setlit(a, here);
	return 0;
}
// assert (c): the failure message carries the line it was written on
fn assert_fail(int line) { put_s("assertion failed on line "); put_n(line); put_c(10); halt(); return 0; }
immediate fn assert() {
	let a, l = tline;
	next(); expect(intern("(")); plainuse(expr()); rval(); expect(intern(")"));
	emitseq(useq[0], ulen[0]);		// not: the jump below skips the failure when it holds
	a = hole(); op(O_JZ);
	lit(l); callname(intern("assert_fail")); op(O_DROP);
	setlit(a, here);
	return 0;
}
// times N { body }: the body pasted N times, at compile time
immediate fn times() {
	let n, b, i = 0;
	next(); n = tv; next();
	b = grab();
	while (i < n) { feed(qdup(b)); i++; }
	free(d*b);
	return 0;
}

fn double(x) { return x * 2; }
fn inc(x) { return x + 1; }
fn main() {
	put_n(5 |> double |> inc |> double); put_c(10);
	unless (1 > 2) put_s("one isn't bigger than two\n");
	times 3 { put_c('*'); }
	put_c(10);
	assert(double(4) == 8);
	assert(inc(1) == 3);
	return 0;
}