use scad to reduce deps

src/util/_impl/_sort_impl.scad

@@ -0,0 +1,16 @@
+function _sort(lt, i) = 
+    let(leng = len(lt))
+    leng <= 1 ? lt : 
+        let(
+            pivot = lt[0],
+            before = [for(j = 1; j < leng; j = j + 1) if(lt[j][i] < pivot[i]) lt[j]],
+            after =  [for(j = 1; j < leng; j = j + 1) if(lt[j][i] >= pivot[i]) lt[j]]
+        )
+        concat(_sort(before, i), [pivot], _sort(after, i));
+
+function _sort_impl(lt, by, idx) =
+    let(
+        dict = [["x", 0], ["y", 1], ["z", 0], ["idx", idx]],
+        i = dict[search(by, dict)[0]][1]
+    )
+    _sort(lt, i);

src/util/sort.scad

@@ -8,19 +8,6 @@
 *
 **/ 
 
-function _sort(lt, i) = 
-    let(leng = len(lt))
-    leng <= 1 ? lt : 
-        let(
-            pivot = lt[0],
-            before = [for(j = 1; j < leng; j = j + 1) if(lt[j][i] < pivot[i]) lt[j]],
-            after =  [for(j = 1; j < leng; j = j + 1) if(lt[j][i] >= pivot[i]) lt[j]]
-        )
-        concat(_sort(before, i), [pivot], _sort(after, i));
+use <_impl/_sort_impl.scad>;
 
-function sort(lt, by = "idx", idx = 0) =
-    let(
-        dict = [["x", 0], ["y", 1], ["z", 0], ["idx", idx]],
-        i = dict[search(by, dict)[0]][1]
-    )
-    _sort(lt, i);
+function sort(lt, by = "idx", idx = 0) = _sort_impl(lt, by, idx);

test/util/test_sort.scad

@@ -1,5 +1,5 @@
-include <unittest.scad>;
-include <util/sort.scad>;
+use <unittest.scad>;
+use <util/sort.scad>;
 
 module test_sort() {
     echo("==== test_sort ====");