1 files changed, 55 insertions, 0 deletions
diff --git a/dynarray.sml b/dynarray.sml
new file mode 100644
index 0000000..0c1cd7f
--- /dev/null
+++ b/dynarray.sml
@@ -0,0 +1,55 @@
+structure Dynarray: DYNARRAY = struct
+  type 'a t = (int * 'a option Array.array) ref
+
+  exception OutOfBounds
+
+  fun create n =
+    ref (0, Array.array (n, NONE))
+
+  fun create0 () = create 10 
+
+  fun length dynarr =
+  let
+    val (len, _) = !dynarr
+  in
+    len
+  end
+
+  fun push dynarr v =
+  let
+    val (len, arr) = !dynarr
+  in
+    if len = Array.length arr then
+      let
+        val arr2 = Array.array (len * 2, NONE)
+      in
+        Array.copy { src = arr, dst = arr2, di = 0 };
+        dynarr := (len, arr2);
+        push dynarr v
+      end
+    else
+      Array.update (arr, len, SOME v);
+      dynarr := (len + 1, arr)
+  end
+
+  fun get dynarr n =
+  let
+    val (len, arr) = !dynarr
+  in
+    if n >= len then
+      raise OutOfBounds
+    else
+      valOf $ Array.sub (arr, n)
+  end
+
+  fun set dynarr n v =
+  let
+    val (len, arr) = !dynarr
+  in
+    if n >= len then
+      raise OutOfBounds
+    else
+      Array.update (arr, n, SOME v)
+  end
+
+end