diff --git a/src/resonant_collinearity.gleam b/src/resonant_collinearity.gleam
index ac94881..c0a4619 100644
--- a/src/resonant_collinearity.gleam
+++ b/src/resonant_collinearity.gleam
@@ -1,7 +1,6 @@
 import gleam/dict.{type Dict}
 import gleam/float
 import gleam/int
-import gleam/io
 import gleam/list
 import gleam/result
 import gleam/string
@@ -71,36 +70,30 @@ fn find_collinear_in_direction(
 
   case direction {
     Forward -> #(
-      float.round(float.subtract(x1f, float.multiply(dx, distance))),
-      float.round(float.subtract(y1f, float.multiply(dy, distance))),
-    )
-    Reverse -> #(
       float.round(float.add(x2f, float.multiply(dx, distance))),
       float.round(float.add(y2f, float.multiply(dy, distance))),
     )
+    Reverse -> #(
+      float.round(float.subtract(x1f, float.multiply(dx, distance))),
+      float.round(float.subtract(y1f, float.multiply(dy, distance))),
+    )
   }
 }
 
-fn points_within_map(points: List(Point), grid: Grid) -> Bool {
-  list.all(points, point_within_map(_, grid))
-}
-
 fn find_forward_harmonic_collinears(
   found: List(Point),
   grid: Grid,
 ) -> List(Point) {
-  let #(head, _rest) = list.split(found, 2)
+  let #(head, rest) = list.split(found, 2)
   let assert [p1, p2] = head
-  case points_within_map(head, grid) {
-    True -> {
+  let collinear_in_direction = find_collinear_in_direction(p1, p2, Forward)
+
+  case point_within_map(collinear_in_direction, grid) {
+    True ->
       find_forward_harmonic_collinears(
-        list.append(
-          list.wrap(find_collinear_in_direction(p1, p2, Forward)),
-          found,
-        ),
+        list.append([p2, collinear_in_direction], list.append(rest, [p1])),
         grid,
       )
-    }
     False -> found
   }
 }
@@ -109,18 +102,16 @@ fn find_reverse_harmonic_collinears(
   found: List(Point),
   grid: Grid,
 ) -> List(Point) {
-  let #(head, _rest) = list.split(found, 2)
+  let #(head, rest) = list.split(found, 2)
   let assert [p1, p2] = head
-  case points_within_map(head, grid) {
-    True -> {
+  let collinear_in_direction = find_collinear_in_direction(p1, p2, Reverse)
+
+  case point_within_map(collinear_in_direction, grid) {
+    True ->
       find_reverse_harmonic_collinears(
-        list.append(
-          list.wrap(find_collinear_in_direction(p1, p2, Reverse)),
-          found,
-        ),
+        list.append([collinear_in_direction, p1], list.append(rest, [p2])),
         grid,
       )
-    }
     False -> found
   }
 }