From 90b0d817fedfa5715b195e16da67fa6bdd67638e Mon Sep 17 00:00:00 2001
From: Kimplul <kimi.h.kuparinen@gmail.com>
Date: Mon, 29 Dec 2025 00:07:16 +0200
Subject: work towards a simple integer vector implementation

+ Hopefully shows that useful programs can be implemented with
  the rules present

+ Still missing at least external functions with non-void returns
---
 examples/vec.fwd | 150 +++++++++++++++++++++++++++++++++++++++++--------------
 1 file changed, 112 insertions(+), 38 deletions(-)

(limited to 'examples/vec.fwd')

diff --git a/examples/vec.fwd b/examples/vec.fwd
index 1cc10b3..6c854d5 100644
--- a/examples/vec.fwd
+++ b/examples/vec.fwd
@@ -1,51 +1,125 @@
+import "../mod/libfwdio.so"
 import "../mod/libfwdmem.so"
 import "../mod/libfwdutil.so"
 
-/* trait */
-any = {}
+vec {
+	u64 n;
+	u64 s;
+	*i64 buf;
+}
+
+init_vec(u64 n, (vec) ok)
+{
+	ok([n => n, 0 as u64 => s, * => buf] vec);
+}
+
+next_s_vec(u64 s, (u64) ok)
+{
+	if s == 0 as u64 {
+		ok(1 as u64);
+	} else {
+		ok(2 as u64 * s);
+	}
+}
 
-/* template */
-vec[any type]() {
-	<> {
-		i64 s;
-		i64 n;
-		*[]type buf;
+reserve_vec(vec v, u64 c, (vec) ok)
+{
+	v => [n => n, s => s, buf => buf];
+	n + c => nn;
+
+	/* expand if we run out of space */
+	if nn > s {
+		next_s_vec(s) => s;
+
+		/* note that fwdrealloc creates a new closure, meaning that it
+		 * takes ownership of v.buf, so we can't back out and do a
+		 * single ok(v) at the end of the function */
+		fwdrealloc(buf, s * sizeof(i64)) => nbuf;
+		ok([nn => n, s => s, nbuf => buf] vec);
+	} else {
+		ok([nn => n, s => s, buf => buf] vec);
 	}
+}
+
+set_vec(vec v, i64 i, i64 e, (vec) ok)
+{
+	v => [n => n, s => s, buf => buf];
+	buf + (n - 1 as u64) => nbuf;
+	nil nbuf {fwdpanic("should never happen");} => dst;
+	e => dst*;
+	ok([n => n, s => s, nbuf => buf] vec);
+}
+
+n_vec(vec v, (vec, u64) ok)
+{
+	v => [n => n, s => s, buf => buf];
+	ok([n => n, s => s, buf => buf] vec, n);
+}
+
+append_vec(vec v, i64 e, (vec) ok)
+{
+	n_vec(v) => v, n;
+	reserve_vec(v, n + 1 as u64) => v;
+	set_vec(v, n as i64 - 1, e) => v;
+	ok(v);
+}
+
+at_vec(vec v, u64 i, (vec, &i64) ok)
+{
+	v => [n => n, s => s, buf => buf];
+	if i >= n {fwdpanic("bounds error");}
+	fwdptradd(buf, (i * sizeof(i64)) as i64) => *i64 buf;
+	nil buf {fwdpanic("should never happen");} => &i64 bufr;
+	ok([n => n, s => s, buf => buf] vec, bufr);
+}
+
+destroy_vec(vec v)
+{
+	v => [n => n, s => s, buf => buf];
+	fwdfree(buf);
+	nil n;
+	nil s;
+}
 
-	<>create((<>) next)
-	{
-		next((0 => s, 0 => n, * => buf)<>);
+populate_vec(i64 i, i64 n, vec v, (vec) ok)
+{
+	if i < n {
+		append_vec(v, i) => vec v;
+		populate_vec(i + 1, n, v, ok);
+	} else {
+		ok(v);
 	}
+}
 
-	<>append(<> v, type n, (<>) next)
-	{
-		v.n = v.n + 1;
-		if v.s == 0 {
-			v.s = 1;
-		}
-
-		if v.n > v.s {
-			if v.s == 0 {
-				v.s = 1;
-			}
-
-			v.s = v.s * 2;
-			fwdrealloc(v.buf, v.s as u64 * sizeof(type)) => ptr;
-			v.buf = ptr;
-		}
-
-		/* in a real implementation this would be moved to after
-		 * fwdrealloc I guess, but this is fine for now */
-		nil v.buf {fwdpanic("no buf for vector");} => buf;
-		buf*[v.n - 1] = n;
-		next(v);
+guard(bool c, () err | () ok)
+{
+	if c {
+		err();
+	} else {
+		ok();
 	}
+}
 
-	<>destroy(<> v)
-	{
-		fwdfree(v.buf);
-		nil v;
+check_vec(i64 i, i64 n, vec v, (vec) ok)
+{
+	if i < n {
+		at_vec(v, i as u64) => v, elem;
+
+		guard(elem* != i) =>  {
+			destroy_vec(v);
+			fwdpanic("vec built wrong");
+		} => ;
+
+		check_vec(i + 1, n, v, ok);
+	} else {
+		ok(v);
 	}
 }
 
-u8vec = vec[u8]()
+main()
+{
+	init_vec(0 as u64) => vec v;
+	populate_vec(0, 1000000, v) => vec v;
+	check_vec(0, 1000000, v) => vec v;
+	destroy_vec(v);
+}
-- 
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