1 files changed, 49 insertions, 0 deletions
diff --git a/examples/lang.zc b/examples/lang.zc
new file mode 100644
index 0000000..6e992b4
--- /dev/null
+++ b/examples/lang.zc
@@ -0,0 +1,49 @@
+// 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;
+}