diff --git a/src/turtle/_impl/_t2d_impl.scad b/src/turtle/_impl/_t2d_impl.scad
new file mode 100644
index 00000000..4a2998bf
--- /dev/null
+++ b/src/turtle/_impl/_t2d_impl.scad
@@ -0,0 +1,61 @@
+function _t2d_turtle(point, angle) = 
+    [is_undef(point) ? [0, 0] : point, is_undef(angle) ? 0 : angle];
+
+function _t2d_set_point(t, point) = [point, _t2d_get_angle(t)];
+
+function _t2d_set_x(t, x) = [[x, _t2d_get_y(t)], _t2d_get_angle(t)];
+function _t2d_set_y(t, y) = [[_t2d_get_x(t), y], _t2d_get_angle(t)];
+function _t2d_set_angle(t, angle) = [_t2d_get_pt(t), angle];
+
+function _t2d_forward(t, leng) = 
+    _t2d_turtle(
+        [
+            _t2d_get_x(t) + leng * cos(_t2d_get_angle(t)), 
+            _t2d_get_y(t) + leng * sin(_t2d_get_angle(t))
+        ], 
+        _t2d_get_angle(t)
+    );
+
+function _t2d_turn(t, angle) = [_t2d_get_pt(t), _t2d_get_angle(t) + angle];
+
+function _t2d_get_x(t) = t[0][0];
+function _t2d_get_y(t) = t[0][1];
+function _t2d_get_pt(t) = t[0];
+function _t2d_get_angle(t) = t[1];
+
+function _t2d_get(t, cmd) =
+    cmd == "angle" ? _t2d_get_angle(t) : 
+    cmd == "point" ? _t2d_get_pt(t) : 
+    assert(false, "unknown command");
+
+function _t2d_set(t, point, angle) =
+    !is_undef(point) ? _t2d_set_point(t, point) :
+    !is_undef(angle) ? _t2d_set_angle(t, angle) :
+    assert(false, "no target to set");
+
+function _t2d_cmdline(cmd, t, arg) = 
+    is_undef(arg) ? _t2d_get(t, cmd) : 
+    cmd == "forward" ? _t2d_forward(t, arg) : 
+    cmd == "turn" ? _t2d_turn(t, arg) :
+    cmd == "point" ? _t2d_set_point(t, arg) : 
+    cmd == "angle" ? _t2d_set_angle(t, arg) :  
+    assert(false, "unknown command");
+
+function _t2d_cmd(t, cmd, point, angle, leng) = 
+    cmd == "forward" ? _t2d_forward(t, leng) :
+    cmd == "turn" ? _t2d_turn(t, angle) :
+    _t2d_get(t, cmd);
+
+function _t2d_cmds(t, cmds, i = 0) = 
+    i == len(cmds) ? t :
+    let(
+        cmd = cmds[i][0],
+        arg = cmds[i][1]
+    )
+    _t2d_cmds(_t2d_cmdline(cmd, t, arg), cmds, i + 1);
+
+function _t2d_impl(t, cmd, point, angle, leng) =
+    is_undef(t) ? _t2d_turtle(point, angle) : 
+    is_undef(cmd) ? _t2d_set(t, point, angle) :
+    is_string(cmd) ? _t2d_cmd(t, cmd, point, angle, leng) :
+                     _t2d_cmds(t, cmd);
\ No newline at end of file
diff --git a/src/turtle/t2d.scad b/src/turtle/t2d.scad
index a84baaf7..5b8838a9 100644
--- a/src/turtle/t2d.scad
+++ b/src/turtle/t2d.scad
@@ -8,64 +8,6 @@
 *
 **/ 
 
-function _t2d_turtle(point, angle) = 
-    [is_undef(point) ? [0, 0] : point, is_undef(angle) ? 0 : angle];
+use <turtle/_impl/_t2d_impl.scad>;
 
-function _t2d_set_point(t, point) = [point, _t2d_get_angle(t)];
-
-function _t2d_set_x(t, x) = [[x, _t2d_get_y(t)], _t2d_get_angle(t)];
-function _t2d_set_y(t, y) = [[_t2d_get_x(t), y], _t2d_get_angle(t)];
-function _t2d_set_angle(t, angle) = [_t2d_get_pt(t), angle];
-
-function _t2d_forward(t, leng) = 
-    _t2d_turtle(
-        [
-            _t2d_get_x(t) + leng * cos(_t2d_get_angle(t)), 
-            _t2d_get_y(t) + leng * sin(_t2d_get_angle(t))
-        ], 
-        _t2d_get_angle(t)
-    );
-
-function _t2d_turn(t, angle) = [_t2d_get_pt(t), _t2d_get_angle(t) + angle];
-
-function _t2d_get_x(t) = t[0][0];
-function _t2d_get_y(t) = t[0][1];
-function _t2d_get_pt(t) = t[0];
-function _t2d_get_angle(t) = t[1];
-
-function _t2d_get(t, cmd) =
-    cmd == "angle" ? _t2d_get_angle(t) : 
-    cmd == "point" ? _t2d_get_pt(t) : 
-    assert(false, "unknown command");
-
-function _t2d_set(t, point, angle) =
-    !is_undef(point) ? _t2d_set_point(t, point) :
-    !is_undef(angle) ? _t2d_set_angle(t, angle) :
-    assert(false, "no target to set");
-
-function _t2d_cmdline(cmd, t, arg) = 
-    is_undef(arg) ? _t2d_get(t, cmd) : 
-    cmd == "forward" ? _t2d_forward(t, arg) : 
-    cmd == "turn" ? _t2d_turn(t, arg) :
-    cmd == "point" ? _t2d_set_point(t, arg) : 
-    cmd == "angle" ? _t2d_set_angle(t, arg) :  
-    assert(false, "unknown command");
-
-function _t2d_cmd(t, cmd, point, angle, leng) = 
-    cmd == "forward" ? _t2d_forward(t, leng) :
-    cmd == "turn" ? _t2d_turn(t, angle) :
-    _t2d_get(t, cmd);
-
-function _t2d_cmds(t, cmds, i = 0) = 
-    i == len(cmds) ? t :
-    let(
-        cmd = cmds[i][0],
-        arg = cmds[i][1]
-    )
-    _t2d_cmds(_t2d_cmdline(cmd, t, arg), cmds, i + 1);
-
-function t2d(t, cmd, point, angle, leng) =
-    is_undef(t) ? _t2d_turtle(point, angle) : 
-    is_undef(cmd) ? _t2d_set(t, point, angle) :
-    is_string(cmd) ? _t2d_cmd(t, cmd, point, angle, leng) :
-                     _t2d_cmds(t, cmd);
\ No newline at end of file
+function t2d(t, cmd, point, angle, leng) = _t2d_impl(t, cmd, point, angle, leng);
\ No newline at end of file